Corona warning app

Corona warning app
	; The Corona-Warn-App is an app that aims to help track and interrupt chains of SARS-CoV-2 (COVID-19 trigger) infection in Germany.
Basic data
developer	SAP & Deutsche Telekom
Publishing year	2020
Current version	1.2.1 ( Android - ; Google Play Store) ; August 12, 2020; 1.2.1 ( iOS - ; Apple Store) ; August 12, 2020
Current preliminary version	1.3.0-SNAPSHOT-RC6 ( Android ) ; August 19, 2020
operating system	Android , iOS
category	COVID-19 app
License	Apache license, version 2.0
German speaking	Yes
	www.coronawarn.app

The Corona-Warn-App has been a COVID-19 app that has been available for download in over 20 languages in Germany since June 16, 2020 and in all EU and other countries since the beginning of July 2020 and uses a variant of contact tracking. The app is intended to inform users whether they have come into contact with an infected person and whether there is an increased risk of infection from this. In this case, users should limit contact with third parties that could pose a risk of infection until their infection has been ruled out by a medical examination. This should help the responsible authorities to trace and interrupt chains of infection and thus contain the spread of the COVID-19 pandemic . The app is published by the Robert Koch Institute (RKI) , and it was developed by SAP and Deutsche Telekom AG with the participation of around 25 other companies. The app uses the interfaces of the Apple and Google operating systems and the protocols of DP-3T and TCN .

History and objectives

Even before the Corona warning app, apps were used in the area of civil defense. These are also known as Katwarn , BIWAPP, and NINA . The warning app NINA is conceptually in MoWaS involved and since April 2020 by BMI recommended for Information Corona dangerous situation.

In spring 2020, against the background of the COVID-19 pandemic, the need arose to develop a warning app to prevent the spread of the pandemic. In the course of the development and use of the Corona warning app, there were numerous controversies and, in some cases, competition with comparable apps from other countries.

Languages and use in other countries

Since the beginning of July 2020, the app can be downloaded from the Google Play Store and Apple App Store in all EU countries as well as from Great Britain, Norway and Switzerland. When it was launched, the app was available in German and English; since the beginning of July 2020, over 20 languages can be selected for download, including Turkish, French, Spanish, Italian, Polish, Romanian, Arabic, Vietnamese and Chinese.

The German app and the technically comparable apps from other countries record the Bluetooth codes of other Corona apps when traveling abroad. But there is currently no interface between the national server systems for an exchange of warnings across national borders.

In June 2020, the EU Commission had therefore already adopted plans to set up an exchange platform within the framework of the e-health network , which should achieve interoperability in this regard . Experts led by SAP and Deutsche Telekom had drafted the concept. At the end of July 2020, these companies received the order from the EU Commission to set up and operate such a software platform.

functionality

Components

Current architecture

The system architecture primarily comprises the app voluntarily installed by the user on the individual smartphones, the "Exposure Notification Framework" (ENF) interface between the app and the operating system in the smartphone, various hotlines for technical questions and for authorizing the message "positive coronavirus Tests "and several web servers installed in the Open Telekom Cloud .

The app has four main functions: the risk determination, the reporting of the positive corona test, the risk assessment as well as the information and recommended action.

How these main functions are specifically determined by the code of the app and the interaction with the code of the Google Apple Exposure Network API and the operating systems of Google and Apple is not completely transparent to the public . Even the information available on GitHub does not all correspond to the current version of the app.

Web server

In accordance with the client-server model , Deutsche Telekom operates four servers for the app:

the Corona-Warn-App-Server. It saves the authorized reports of positive corona tests as long as they are not older than 14 days.
the verification server. It documents that a user has voluntarily agreed to submit the report about his positive corona test and that this report has been confirmed as correct ("verified") by the laboratory.
the portal server. It generates teleTANs for health authorities and laboratories that are not yet digitally connected to the app system.
the test results server. He makes the results of the laboratories available for further use.

The distribution of the data to several servers is intended to decouple this data and thus make it difficult to trace back to individual users.

Risk assessment

If a person has switched on the "risk identification" function in the app menu, the smartphone with Bluetooth Low Energy sends identifiers (rolling proximity identifiers, RPI) up to four times per second. The identifiers are encrypted in different ways in the smartphone at short intervals from a key that is changed at midnight UTC (“daily key”). At the same time, the app checks whether there are other smartphones in the vicinity that the app also sends out such identifiers. If this is the case and conditions are met for this contact which, according to the RKI, exceed a limit value, the IDs, signal strength, date and time and the duration of reception are stored on the receiving smartphone for 14 days. The briefly changing encryption of the sent IDs is intended to obscure the identity of the sending smartphone or its user.

Report of the positive corona test

In the “Overview” menu, the app primarily contains the “Notification of others” function. This means that a test that has made a current infection with the SARS-CoV-2 pathogen probable ("positive corona test") can be voluntarily and anonymously registered in the Corona warning app server to warn contact persons: Usually this test is an RT-PCR test . A person with such a test result is called "Corona-positive" (simply called "currently infected" or "new infection"). If the health department or test laboratory is already digitally integrated into the structure of the system set up for the app, it sends the person who tested positive for corona a QR code after checking in the verification server . She can then voluntarily read the QR code into the app. As long as the health department or test laboratory is not yet digitally integrated in the app system, the positive corona test must be reported via teleTAN via a verification hotline . In both cases, the app then uploads the message of the positive corona test to the Corona warning app server after the user has given his consent.

In addition, the status and result of a corona test can be queried via the “Overview” menu after the sample has been submitted, provided the laboratory is technically equipped for this.

Risk assessment

If the smartphone user has switched on the "Send notifications" option in the app menu, the app automatically downloads the list of all daily keys for those smartphones once a day based on a timer in the app by polling the Corona warning app server which positive test results were saved there in the last 14 days. The "Exposure Notification Framework" (ENF) interface , which Apple and Google agreed on at the beginning of 2020 especially for Corona warning apps with decentralized storage and which is therefore available in their newer versions of the operating systems, is then transmitted to the querying smartphone the IDs (RPI) of the people with a positive corona test from the downloaded daily keys. If identifiers of neighboring smartphones have been recorded and saved via the BLE function of the smartphone, a check is then carried out to determine whether some of them correspond to those identifications that were received and stored by neighboring smartphones in the last 14 days.

First of all, the value of four parameters is weighted separately for each day and exchange with the app data of another smartphone: day and duration of the encounter, estimated distance between the smartphone and the “risk of transmission” of the person at risk. The RKI can use updates to transfer changed weightings to the app based on newly acquired knowledge .

The risk is then determined in a multi-stage process, which results from the total time of all risk encounters over the last 14 days. At the end of the day, the app always notifies the user of an "increased risk" if this risk exceeds a limit value. The assumptions about this limit value and the algorithms used can be changed at any time by the RKI "on the basis of research results". The research results, the conclusions about the app and the implementation in rules are not described on GitHub or otherwise published in writing. At the end of July, according to verbal information from developers of the app and epidemiologists of the RKI, the procedure includes

First of all, all encounters that lasted less than 10 minutes, were more than 8 meters away or were longer than 6 days from the time of the warning are filtered out. The RKI admits that BLE also measures the duration of the encounters inaccurately because it only scans the environment for two to four seconds every five minutes to save battery power. Therefore, if the time slots of the scans are unfortunate, the actual encounter duration can be up to 15 minutes, although the recorded duration is only 10 minutes. In addition, the time of the warning, not the first symptoms or even infection, is used because the date of the first symptoms has not yet been recorded and the infection is usually unknown. An increased infectivity is assumed from two to four days after the warning, and a lower one for the first, fifth and sixth days. From the seventh day since the warning, the RKI considers encounters with corona positives to be insignificant.

In the second step, the app calculates a “fictitious duration” of all encounters that have not yet been filtered out as a risk value. The app adds the actual duration of these risk encounters and weights them with correction values. These should "appropriately" take into account the interval and the number of days that have passed since the encounter until the warning was sent. If the fictitious duration is more than 15 minutes, the app display turns "red", if it is less than 15 minutes, the app remains "green". However, if the encounter with a corona-positive person was two to four days ago since the warning, ten "fictitious" minutes at a distance of up to 1.5 meters are enough to color the app "red". One or two encounters with 20 actual minutes are necessary at a distance of 1.5 to 3 meters. If, on the other hand, encounters with corona positives have been six days since the warning, the time before the app switches from “green” to “red” can increase to up to five encounters at a distance of three meters with a total of 50 actual minutes. If several encounters with corona positives were recorded on different days, the app for calculating the fictitious risk duration assumes that all encounters with corona positives occurred on the saved day with the highest infectivity.

When it comes to the distances to corona-positives, half of the encounters which, according to the BLE, took place in "up to three meters" are upgraded as encounters "up to 1.5 meters".

Information and recommendation for action

Starting about one day after installation, the app begins to report on the result of the risk assessment on its home page and, depending on this, to give recommendations for action:

Increased risk: The user is informed that there is an increased risk of infection because he / she had risk encounters with at least one person who tested positive for Corona in the past 14 days. In order to make it more difficult for the warned person to identify the person at risk, only the day and not the time of the encounter is communicated. The person is also recommended to go home or stay at home, if possible, and to contact their family doctor, the on-call medical service on telephone number 116117 or the health department and agree on how to proceed.
low risk. This message is issued if enough time has passed since the app was installed and the "risk assessment" option was activated, but the risk assessment did not lead to the "increased risk" result. The message is also issued when the risk assessment The assessment did not lead to the result "increased risk" because identifiers were not exchanged. The app informs the person that the risk assessment did not result in an encounter with people who were proven to be Corona-positive or that any encounters did not exceed the defined threshold The person is also informed about generally applicable distance regulations and hygiene recommendations.
Unknown risk: This message appears if not enough time has passed since the app was installed and the "Risk determination" option was activated.

These risk reports are not always justified: If, for example, the device has no BLE function or no BLE function switched on, identifiers from neighboring smartphones cannot be received and thus cannot be compared with daily keys. Nevertheless, the app then reports "low risk" instead of applicable "unknown risk" and incorrectly "risk determination permanently active" on a green background.

The app has not yet indicated that it can be queried whether and, if so, how often and on what day at what time in the last 14 days your own smartphone has downloaded the daily key from the Corona warning app server. This information can not be found in the app, but in the "Settings" menu of the device:

on iPhones in "Settings", then "Privacy and Health"> "Covid-19 Contact Log"> "Contact Reviews"
On Android devices in “Settings”, then “Google”> “Covid-19 notifications”> “Check for possible encounters”. The password of the Google account must be entered beforehand.

However, the information listed there does not provide any information as to whether and, if so, with what result the downloaded daily key was compared with the contact data stored on the smartphone. Therefore, downloads of daily keys are also listed here if a risk assessment could not be derived from them, for example because the smartphone has no or no suitable Bluetooth hardware.

conditions

Position of the European Parliament

The resolution of the EU Parliament of April 17, 2020 on "coordinated EU measures to combat the COVID-19 pandemic and its consequences" called for:

The use of applications developed by national and EU authorities must not be mandatory - an exclusion of the obligation by law is being discussed in Germany
The entire data storage must be decentralized - only the daily keys of smartphones for which an infection has been authorized are stored on the Corona warning app server for 14 days; their encryption is intended to prevent the smartphone from being identified
Clear prognoses have to be presented about how the use of apps to identify contact persons by part of the population in conjunction with specific other measures will lead to a significantly lower number of infected persons - such prognoses and also initial evaluations from other countries, which are tracing -Apps have also been introduced, come to conflicting results

German law

Authorities, government and providers point out that the use of the app is voluntary and people who do not use it should not be discriminated against. A legal clarification in this direction was rejected by the federal government.
There are various details about the age limit: In its version for Apple devices, the app should only be used by people aged 17 and over. For Android devices, however, the app is labeled “FSK; from 0 years "classified. In the app itself, the terms of use say: “The app is aimed at people who are at least 16 years old. People under the age of 16 may only use the app with the consent of their legal guardian ”. The data protection declaration states for both the Android version and the iOS version: "The app is aimed at people who are in Germany and who are at least 16 years old".
The app can only be regularly installed on Android devices via country versions of the Play Store, for which the RKI has now been able to meet the national legal requirements. It is therefore not available to Android users from other countries via the Play Store, even if they are in Germany. The reasons given are legal (data protection) considerations.
The use of the app does not replace measures that are stipulated in the Infection Protection Act (IfSG) with regard to COVID-19 , including the collection of extensive personal data from people for whom there is reasonable suspicion of illness, illness and death from COVID-19, and the reporting of this data to the state authority and from there (except for mere suspicious cases) to the RKI or, in the case of certain people, to the Bundeswehr.
A warning from the app
- In terms of labor law, this is not a sick leave, but only an indication to contact the health service.
- does not mean that the warned person is a "contact person of category I, II or III" as defined by the RKI for other purposes. This classification requires further data.
If the app detects an "increased risk of infection", then
- Those affected can have a smear taken from their doctor to also test for the coronavirus. The health insurance companies bear the costs. In Bavaria, PCR tests are offered free of charge without any cause, in other federal states this is rejected with reference to false-positive test results that are then frequent .
- the recommendation to go home or to stay at home is not an official order for quarantine.
- this alone does not meet the definition of a justified suspicion within the meaning of the IfSG. Rather, it is the task of the doctor visited to decide on the basis of questioning and examination and to initiate further measures based on this.

Technical requirements

General

Smartphone-sized devices : so far, the layout of the app interface has not been adapted for tablets or wearables

Send and receive Bluetooth Low Energy (BLE): to exchange the identifiers. If the device has no, no suitable or no functioning Bluetooth hardware, the installation still takes place without warning. After installation, there is no indication of this fact in the app menu, but only the non-targeted information that Bluetooth must be "activated" and the "risk determination" is limited.

Camera: to read the QR code to confirm the infection

Internet connection: to receive the QR code, to authorize the positive corona test in the verification server, to save the positive corona test in the Corona warning app server, to upload the daily key to the Corona warning app Server and to query the daily key in the Corona-Warn-App-Server

Telephone number: for receiving an SMS with TeleTAN when using the verification hotline

Android

a Google account: to use the Google Play Store
approx. 19 MB storage space for installing the app on Android
Android version 6.0 ("Marshmallow") or newer: since API level 23, published in October 2015, only supports the Exposure Notification Framework.
Google Play Services: so that the Exposure Notification Framework can be installed - which is not standard with newer devices from China ( e.g. from Huawei for licensing reasons ). Huawei builds the necessary interface into the operating system itself via Huawei Mobile Services .
The "rough location determination" based on WiFi or cellular data must be activated on some devices, but the app developers assure that neither the app nor the interface to the operating system make use of this.

Apple

an Apple account: to use the app store
initially German Apple ID: the app was initially only available in the German app store, which made it impossible for travelers and international students, for example, to use it
about 31 MB of storage space is required to install the app under iOS
iOS 13.5 or newer: This means that the iPhone 6s, which came onto the market in September 2015, or later models are suitable, as the interface required for tracking encounters using the Exposure Notification Framework API was only introduced with iOS 13.5
Parental controls must be deactivated: the app is rated "17+" in the Apple App Store

Expectations and acceptance

In an ARD Germany trend carried out by Infratest-Dimap before the app was launched , 42 percent of respondents announced that they would use such an app. The most common reason for rejection was data protection.

Two surveys date from the time after the app was launched:

In the above-mentioned survey by the YouGov survey institute from June 17 to 19, 2020, among those surveyed who had not yet installed the app, the most common reason (27 percent) was “I don't think the app is anything useful ”, closely followed by 26 percent who are concerned about their data and 25 percent who would feel that they were being monitored by the state. With a gap of 21 percent, this is followed by the reason that the smartphone's Bluetooth must be permanently switched on to use the app. Other often-mentioned reasons for not having installed the app so far were, with 19 percent each, “I don't want the app to follow who I meet”, “I think the Corona issue is being exaggerated” and “I want to wait and see until others have tested the app / reported on their experiences ". Only afterwards are reasons such as a smartphone that is too old or not available (13 percent) and concerns about battery consumption (13 percent). 10 percent felt that they were not sufficiently informed so far. Only 8 percent wanted to install the app back then.

According to a survey by the ZDF Politbarometer on June 26, 2020, only 38 percent assume that the Corona warning app will make a major contribution to limiting the pandemic in Germany, but a majority of 56 percent doubt this.

Initially, the Android version of the app received good ratings from users. By the beginning of August 2020, however, there was a deterioration to only 3.4 out of a maximum of 5.0 points in over 70,000 reviews.

At the same time, however, the Apple version of the app was rated significantly better than the Android version in the App Store with 4.5 out of a maximum of 5.0 points in over 46,000 reviews.

In a Bitcom survey in the first week of July 2020, 53 percent of the 1005 respondents aged 16 and over said that they want to use the Corona app permanently, around 47 percent of those questioned were against permanent use.

In a YouGov survey from the beginning of July 2020, 63 percent of the 2,501 respondents aged 18 and over said that they did not use the Corona warning app. Only 15 percent of the respondents stated that they had used the app at the time of the survey and were convinced that it helps to trace infection chains. Meanwhile, around 5 percent said they used the app, but did not (rather) believe that it would help in the fight against the virus.

Downloads

The great attention that the app received on the day it was launched also resulted in high download figures in the Apple App Store and Google Play Store in the days that followed.

By June 17th, one day after the app launched, there were 6.5 million downloads and after 70 days, by August 25th, there were a total of 17.5 million downloads.

Distribution to the operating systems

The app was offered for download for the first time for Google's Android and Apple's iOS on June 16, 2020, almost simultaneously. In the first five days, the then between 10 and 11 million downloads were distributed roughly equally across both operating systems. However, market researchers estimate that Google's Android has a share of around 75 percent of the German smartphone market, Apple's iOS only the remaining 25 percent. The downloads for iPhones were about twice as high as their market share. Social and technical reasons are suspected for this considerable difference: iPhone users could be more “update and app-happy” than users of Android devices and Apple devices were more often compatible with the app than Android devices. As a result, the relative preference for Apple devices did not decrease: by August 25, 2020, the app had been downloaded around 8.2 million times from the Apple App Store and around 9.3 million times from the Google Play Store.

impact

The download numbers of around 17 million are high compared to the numbers for corona tracing apps in some other states . Of the 83 million people in Germany, around 20 percent have downloaded the app. However, the actual use is decisive for the effectiveness .

use

The actual use of the main functions of the app determines the possible number of warnings and, together with the reliability and timeliness of the warnings, is decisive for the effectiveness and admissibility of the entire procedure under data protection law. With a usage rate of 15 percent, assuming an even distribution of usage across the population and contacts between them, two people with the app used meet only in two out of a hundred cases, even with 40 percent usage, the warning app would be based on the same assumptions record only 16 percent of social contacts.

The ratio between people who tested positive and who published diagnostic keys and reported new infections is currently around 6 percent. This means that only 6 percent of all risk encounters can be recognized as such by a corona warning app. For example, if the app were already 50 percent widespread in a certain environment, a warning would only be issued there for 3 percent of all risk contacts.

Information provided by the editor

The RKI announced at the beginning of July 2020 that it would publish user numbers "soon". This has not yet happened without a reason, not even in the continuously updated reports of the RKI on the interim status of the app. Information that suggests the use of the app is therefore only available on non-official websites.

Comparison with the Swiss app

The Swiss app SwissCovid is similar to the German app; aspects of data protection and analysis are specifically regulated there by law and regulation. In contrast to the RKI, the Swiss Federal Statistical Office (FSO) publishes usage data for SwissCovid on the Internet every day. According to this, the usage rate of the Swiss app, measured by the automatic contact between smartphones and the app server, has long been between 60 and 62 percent. The Swiss app received a better rating in the Google Play Store with 3.9 out of a possible 5.0 points than the German app with 3.3. If the Swiss data is used as a benchmark in the absence of data from the RKI, then at best 12 percent of the German population use the Corona warning app.

Influence on effectiveness

In the latest version of the “Oxford Study” , the authors explain that the effectiveness of a tracing app is determined, among other things, by the square of the usage rate in the respective population (“The efficacy of contact tracing (...) is the square of the proportion of the population using the app ").

Consistent with this, the Advisory Council for Consumer Issues at the Federal Ministry of Justice and Consumer Protection points out the connection between use and effectiveness in its report on the app, which is available for download two weeks later: Even with a usage rate ("coverage") of 60 percent and under numerous favorable assumptions that do not apply to Germany, 64 percent of the critical contacts would still be "overlooked" by the app. App users might believe that the resulting missing warnings (“green area”) are a sign that they cannot be infected. One possibility, on the other hand, is that “the app informs every app user about the proportion of potentially infectious contacts that have not been recorded on a daily basis”. So far, however, the RKI has not published how high the user quota is , nor has the advice given by the Expert Council been displayed in the app.

The SVRV recommends that the app be introduced quickly, primarily in order to learn from it at an early stage for a second wave of infections. The SVRV believes that coverage of at least 33 percent is necessary for effective learning. Accordingly, a considerably higher value would have to be expected for effective containment of infections. Lucie Abeler-Dörner, one of the co-authors of the Oxford study , came to a much more optimistic assessment in an interview with the Süddeutsche Zeitung. She concluded that an app began to work under the conditions simulated in the study when only 15 percent of the population used it. This statement was taken up by other German media without taking into account the fundamentally different conditions when the local app was introduced. In addition, the effect estimated by the authors is only minor: if the download rate of the German app was used in full (around 20 percent at the beginning of August), the app would only reduce the reproduction factor R by around 0.08 according to the British model, which is lies within the regular fluctuation range of the R-value of one week and would therefore hardly be noticeable in the short term. In addition, in articles from renowned newspapers, the download rate was wrongly equated with the (unknown) usage rate.

In a study in the Harvard Business Review from July, the authors explain: The problem is that the app has to be used almost everywhere in order to be effective. (“The problem is that to be effective, apps need to be nearly ubiquitous.”) “If only a small percentage of the people the user comes into contact with use the app, the app is worthless or even harmful: the ad the app is highly inaccurate and could give a false sense of security. "(" If only a small proportion of people a user comes in contact with are using the app, the app is worthless or even harmful: The app's indications will be highly inaccurate and could even instill a false sense of security. ") Therefore, communities such as companies, universities, religious communities, restaurants and means of transport should" ensure "the use of the app, if necessary also through an obligation (" mandate ").

At the end of August 2020, at the time when new infections were on the rise, the German Advisory Council on Consumer Questions repeated its assessment from June 2020: "So that the Corona warning app really does something", the number of downloads should double. Then you are much better prepared for a second wave. In purely mathematical terms, if an infected person comes into contact with a stranger, the probability that both people will have the app is only six percent. Even if the number of users doubled to 50 percent, their influence would be limited: Only 25 percent of infections would then be detected by the app - provided that all users with a positive corona test report this via the app.

Influencing variables

Not every download actually leads to the use of the different functions of the app. There are reasons to download the app more than once, for example if someone has more than one smartphone or for test purposes. In addition, not every owner has their smartphone turned on and with the “risk determination” function activated. In addition, the ownership and use of smartphones and the installation and use of the app are likely to differ depending on social conditions, for example less often among older people than younger people. Finally, there is also the fact that people like to meet with their own kind, i.e. in subpopulations , differentiated for example by their attitude to technology, origin, religion, education and social status. The app will record encounters and assess risks with different degrees of probability.

Biographical and socio-economic barriers

In Germany, when the app was launched, a little more than 50 million people, i.e. only around 60 percent of the population, owned a smartphone that was technically suitable for using the Corona warning app. The majority of people whose smartphones are unsuitable for installing the app are older than 65 years. More than ten million people over 65 do not have a smartphone. According to the experience of the head of a health department, people who live in a socially deprived area under poor conditions and sometimes also “uneducated” and in a certain isolation from others may have cell phones, but will not benefit from the Corona warning app.

Politicians like Robert Habeck and Franz Müntefering therefore criticized the fact that the app leaves out older people or people with little money.

Parameters

Retrieval of the teleTANs

In the period from June 16 to August 24, 2020, the number of all teleTANs issued via the hotline to verify a positive test result in the verification server was only 2,103. However, this number does not provide information on whether the test result was actually entered by the user in the app. The total number of positive tests reported to the RKI is more than 20 times higher, so only a fraction of the officially recorded positive tests can have been made available in the app for warnings from contact persons. With the increasing digital connection of laboratories and health authorities to the app system, it is to be expected that positive test results will be verified less with TeleTANs and more with QR codes. Nevertheless, in the first few weeks since July 6, 2020, the number per day increased significantly less than in more recent times.

Available positive corona tests

Information on non-official websites shows: In the period from June 23 to August 28, 2020 there were (estimated after deduction, presumably after the deduction of fake reports added to conceal fictitious reports), only 2,379 people who "shared" their diagnosis keys, i.e. after authorization the hotline or the QR code had their positive corona tests entered in the corona warning app server. In the same period, however, 49,178 positive corona tests ("new infections") were reported to the RKI via the state authorities. This means that only just under 5 percent of the officially known positive corona tests have now been reported via the app and are therefore made available in the app for warnings from contact persons. At least there is a trend towards an increase in the 7-day moving average.

Available day keys

Every positive corona test entered in the Corona warning app server actually contained an average of only about 10 daily keys of the 14 possible ones in the aforementioned period.

Retrieval of the daily key

For risk assessment, the app loads all daily keys from the Corona warning app server into the smartphone. This should be done automatically, i.e. without user intervention, once a day and is therefore an indication of the total number of apps used on the respective day with a connection to the Internet. According to Linus Neumann, Deutsche Telekom can determine the number of daily keys downloaded from its Corona server. The RKI has not yet published this notice on the use of the app . The usage rate of the comparable Swiss app “SwissCovid” has long been specified by the authorities there at 60 to 62 percent, according to initially higher values.

Output of warnings

How many app users finally received warnings of what type due to the comparison of the retrieved daily keys cannot be determined, because the comparison and then the risk assessment take place decentrally on the users' smartphones.

Risk of transmission to the risk person

One of the four parameters in the risk assessment of a contact is the "transmission risk level" (TRL), which results from the characteristics of the infected person. The RKI assesses this risk in eight levels. One of the criteria published by the RKI for the classification of the TRL is the infectiousness of the risk person, derived from the time of the corona test. However, the RKI does not provide an explanation of the exact manner in which it derives the risk classifications and, if applicable, from which other specific data. The distribution of the risk levels estimated by the RKI is noticeable: totaled for now over 120,000 assessed daily keys (RPI), the RKI adopted: level 1 (lowest risk) with 48 percent, level 2 with 0 percent, level 3 with 8 percent, Level 4 without allocation, level 5 with 8 percent, level 6 with 10 percent, level 7 with 0 percent, level 8 (highest risk) with 26 percent. The RKI does not explain the gross discontinuity in the distribution. If the RKI's assumptions are correct, then the risk of infection at the time of the warnings was mostly low and the effectiveness of the warnings was therefore limited.

Calls to the hotlines

In the period from June 16 to August 24, 2020, around 240,000 calls were made to the technical hotline and the verification hotline of the Corona warning app, i.e. around 3,500 daily.

Survey

Surveys that were carried out after the app was launched on the scope of download, intended and actual use show that many of the responses deviated significantly from reality in terms of social desirability :

The survey institute YouGov conducted in the period from 17 to 19 June 2020 in Germany a population representative survey. At the time, 25 percent of those surveyed stated that they had already installed the Corona warning app on their smartphone. In fact, at that time the number of downloads was only less than 14 million, i.e. only 17 percent with an even distribution over 83 million inhabitants.

In a telephone survey on June 23 and 24, 2020 among people aged 18 and over by the Federal Institute for Risk Assessment , 28 percent of those questioned stated that they actually "use" the app. In fact, the download rate at that time was still below 16 percent.

In a representative telephone survey in the first week of July 2020 among people aged 16 and over on behalf of the Bitkom digital association , 53 percent of smartphone users said they wanted to use the app permanently, which corresponds to 28 million people. More than a week later, however, the number of downloads is only slightly more than half of this declaration of intent.

reliability

Recording of the duration and proximity of the contact

Since smartphones use this app to estimate the distance to one another based solely on the strength of the Bluetooth signal, errors can occur. Representatives from SAP and Deutsche Telekom, themselves involved in the development of the app and recipients of one-off and ongoing state payments for the development and infrastructure of the app, stated when the app was introduced that in tests in several typical situations a total of around 20 percent of the encounters were wrong have been classified. The tests would have simulated typical situations “like a train ride” or a cocktail party. In addition, the app was "tested on all currently available devices". At the same time, however, two studies by investigators at Trinity College Dublin had revealed serious deficiencies in the distance measurement in buses and trams: At distances and in times that, according to the rules of the German and Swiss apps, should have led to contacts being recorded, these stayed completely off. The authors attributed this to interference caused by reflections on the metal structures of the vehicles. German media reported on the two Irish studies only about two months later. The result is "devastating": Under optimal conditions, in which all passengers have activated the Corona warning app, not a single contact would be registered. The RKI initially did not comment on this. However, without comment, it removed the statement on its website that the app could record contacts “for example in local public transport”. The RKI then objected that the Irish studies had not yet been checked by peer review, and admitted that further measurements were planned in different test scenarios “to improve the reliability of the app”. However, the app will never be able to replace a risk assessment using common sense.

Basically, when using BLE for contact investigations, on the one hand, false-positive reports can occur, for example when people with smartphones are separated by a thin wall or pane of glass. The apps of the devices could register this as a critical contact, although the wall or glass pane prevents the virus from being transmitted. False-negative reports can occur, for example, because Bluetooth is not radiated in an ideal cone but in a club-like shape from smartphones. The receiving smartphone can therefore estimate a greater distance from the signal strength than it actually is if it is located abeam the transmission cone. The distance is also overestimated if the smartphones are carried by the user in such a way that the Bluetooth signal has to pass through the owner's body or a bag on the way to the receiving smartphone, for example. After all, the app cannot determine whether an encounter takes place under conditions that make the transmission of pathogens difficult: in the open air, in physical calm and in calm air. On the other hand, the risk is increased, for example, in a closed room (restaurant, transport) and by a flow of air from the infectious person to the contact person (fan, unsuitable air-conditioning system). The aerosols that are distributed during exhalation are also more numerous and are distributed further when speaking, singing and exercising loudly.

Neglecting multiple sub-critical encounters

The multi-stage process for risk assessment makes a series of assumptions, through which encounters with individual risk persons on individual days are assessed as not significant. For example, encounters of less than 10 minutes and / or an estimated distance of more than about eight meters are currently rejected as "harmless". If, for example, someone sits at a table just under the critical duration during an event or a meal, at which several risk persons are sitting in close proximity at the same time, the algorithm still does not calculate the resulting risk as "increased".

Gaps in reception

The app causes BLE to send its own identifier (RPI) four times per second. But to limit the load on the battery, the app only receives 2 to 4 seconds at a time with pauses of up to 5 minutes in order to capture IDs from the app of other smartphones. In this way, even close contact with highly infectious people can escape detection.

Reliability of test results

The usefulness of the Corona Warning app depends on the positive and negative predictive value of the positive Corona PCR tests reported by the app users. This predictive value is decisively influenced by the prevalence, i.e. how often there are people with a positive corona test among those examined. Even with a very good specificity of 99.9 percent, for example, PCR tests with a prevalence of currently less than 1 per mille in Germany (including an exemplary low number of unreported cases of factor 4) would produce a false-positive result in more than 50 percent of cases , if independent of suspicion randomly selected people would be tested. Federal Minister of Health Jens Spahn , politician from CDU , SPD and Bündnis 90 / Die Grünen from seven federal states and the Association of Accredited Laboratories in Medicine (ALM) conclude that testing all citizens without medical indication (“without cause”) does not make sense . In mid-August 2020, the Association of Laboratory Doctors repeated its advice: “The number of false negatives and, from a statistical point of view, also false positives, increases [...] with the number of tests, especially in the case of mass examinations of completely asymptomatic people. We can already see that travelers returning home show a negative test on arrival, but are tested symptomatically a few days later. Such mass unprovoked tests only lull people into a false sense of security ”.

With regard to the Corona warning app, the occurrence of false-positive tests is of particular importance because there is currently no possibility of deleting positive tests once entered in the verification server if a repeat test has not confirmed the first test.

This not only results in avoidable economic and social disadvantages. In its data protection impact assessment for the Corona app, the Forum for Computer Scientists for Peace and Social Responsibility judges: "Without the ability to intervene [...] the protection of fundamental rights is at risk: There is a high risk of falsely registered exposure events (false positives through walls, Masks or laboratory errors), which would result in wrongly imposed self-quarantine. In order to counter this, legal and factual possibilities for effective influence are required, such as recalling false infection reports, deleting incorrectly registered contact events [...] "

Timeliness

Course of disease of COVID-19

The concept of the app cannot prevent a person (“index patient”) from infecting contact persons (generation 1) before the app warning was issued. But the aim of the app is that such contact persons go into quarantine before their own symptoms due to the app warning and thus prevent them from infecting other people (generation 2), i.e. continuing the chain of infection. In order for this to be possible, the app warnings regarding some parameters of COVID-19 must be given in good time:

When pathogen SARS-CoV-2, the duration is from infection to onset of infectivity for parties latency , as estimated by the Robert Koch Institute, on average, only about 2 or 3 days in the first COVID-19 hotspot of Germany under the company's employees Webasto and their relatives were only there for 1 to 2 days. In contrast, the incubation time for this virus is around 3 days longer on average, a median of 5 days. The RKI therefore assumes that with COVID-19 "a considerable proportion" of those infected have infected other people before symptoms appear; according to a large study, the figure is around 44 percent.

Even if the warning reaches the contact person on the same day on which the person at risk noticed the first symptoms, the time window for a timely warning is already closed in about half of the cases. Therefore, in its third version, the Oxford study also points out the need for the smallest possible delay between noticing the first symptoms by the person at risk and warning their contact persons in their simulations. As part of the immediate contact tracing ("instantaneous contact tracing") propagated by the authors, a corona test should not only be carried out on the person at risk on the day of the first symptoms, but the result should also be communicated to the person at risk and all contact persons through the app will be warned. Those warned should then also receive a corona test on that day and go into self-quarantine for 14 days.

In German reality, however, the processes between the occurrence of symptoms in the person at risk and the warning of their contact persons usually take several days, even if the process is regular: The person at risk makes contact more or less quickly depending on the clarity of the symptoms a doctor or the health department. The smear is taken there. It can take two days or more until the findings are available in the laboratory and the tested people receive the message about their results at home. For the decision to report this diagnosis, the authorization of the diagnosis via QR code or via hotline with comparison in the verification server, the storage of the daily key in the Corona warning app server and the daily retrieval of the daily key by the The contact person's smartphones continue to pass, including the days with the highest virus load before the symptoms begin.

In the interim solution Hotline come to notice for Timothy Höttges "up to four days," which will "(are) super critical when it comes to the spread of the virus to implement measures".

In fact, even at the end of May 2020, i.e. in the epidemiologically quiet times after the first wave of pandemics in Germany had subsided, for additional reasons, the information about positive corona tests was very often late arriving nationwide: from the first symptoms to At that time, reporting to the health department took an average of at least one week in almost 40 percent of the districts. In some cases it even takes more than two weeks. The reasons were varied: delays in the tests, reports and data transmission or simple input errors, including delays in doctors' offices and laboratories, lack of test capacities and the behavior of the patients themselves, who may take days to see a doctor.

At the beginning of August 2020, at the beginning of the wave of many citizens returning home from vacation in risk areas abroad, there were further massive delays and data losses in the information about the results of corona tests, especially in Bavaria. The main reason for this was inadequate IT equipment. Around 44,000 people returning from travel only received their test results weeks later, of which more than 900 were positive cases. Almost 50 positive findings could no longer be assigned to any person.

Shortly afterwards, individual laboratories and their associations sounded the alarm for another reason: The number of tests sent in weekly had risen from almost 600.00 at the end of July to almost 900.00 in mid-August, among other things because of the partly voluntary, partly mandatory tests for travelers returning and at the beginning of the school year . That was predictable, announced and politically wanted. But in the week of August 10th to 16th, the registered laboratories reported a backlog of 17,142 samples to be processed. The reasons given were overloaded capacities and delivery difficulties for reagents for the PCR tests. The positive rate per test was around nine percent at the beginning of April 2020, but since the beginning of June 2020 it has only been around one percent as a result of the expansion of the tests. The interest group of accredited medical laboratories in Germany (ALM) criticized an "uncritical and non-targeted expansion" of the PCR tests. This could put the specialist laboratories in distress. The RKI stated that it was necessary to prioritize the use of the tests.

Another source of delayed warnings are errors in the app: There is an error "API39508" in the Google version, which means that risk notifications are no longer made for longer than 24 hours because "the Corona warning app is the exposure Notification Framework called too often ".

Overall, it can therefore be assumed that the warnings from the app often come too late in order to prevent third parties from being infected by the warned person, i.e. to interrupt the chain of infection. This is also supported by the risk of transmission of the person who triggered the warning, as assessed by the RKI itself : in almost half of the cases, this person was hardly at risk at the time of the warning.

Technical problems

Insufficient digital integration

At the beginning of 2012, the German Bundestag decided to set up an IT system for infection protection, which was eventually named the German Electronic Reporting and Information System for Infection Protection (DEMIS) , and the project began in early 2016. On June 4, 2020, the RKI announced that DEMIS was currently being developed by the RKI and the Federal Ministry of Health (BMG) together with gematik and Fraunhofer FOKUS "under high pressure", but that it was not yet ready for use. Due to the large number of SARS-CoV-2 test results, the non-personal reports required by Section 7 (4) IfSG would “not initially have to be made” because the reports “cannot be processed practically” without DEMIS.

On June 16, 2020, Timotheus Höttges , CEO of Deutsche Telekom, stated without reference to DEMIS that “all test laboratories and all health authorities would be integrated into the digitization process within four weeks”. This would save up to four days, which are "super critical" with regard to the measures against the spread of the virus. So far, almost 80 percent of the large test capacities have not yet been digitally adapted to the app system. According to the RKI, at that time 85 percent of the resident laboratories were not connected digitally, in mid-July 2020 only less than 40 percent. In such cases, the examined persons will receive notification of the positive PCR test by letter and then have to call a "verification hotline": 0800 754 000 2 (free of charge from Germany). This is not identical to the hotline for technical questions (last digit 1). Psychologically trained employees from a call center committed as an external service provider then check the information provided by the calling persons about their positive PCR test. This is to ensure that contact persons are only notified if a test actually turned out positive, i.e. the report was not made in error or improperly. Finally, the person examined is asked to provide the phone number of an SMS-enabled phone or smartphone. The hotline sends a "TeleTAN" as an SMS to this device, which the examined person transfers to the app, which is then used to make an entry in the verification server. However, the call, the answering of the questions and the specification of the phone number of a TeleTAN-enabled device do not allow anonymity. From a data protection perspective, this is “not a good solution”. The RKI and the Federal Ministry of Health would therefore have to create the necessary conditions "as quickly as possible" so that the anonymous procedure via the QR code can be used by as many app users as possible.

At the end of July 2020 it was announced that DEMIS had entered the test phase and the rollout in the health authorities had started. Currently, however, only around ten laboratories are connected to the DEMIS. One is "hopeful that in early autumn, around mid-August, the reporting path between laboratories and health authorities was established". Until then, the data transfer of notifiable illnesses will usually continue to be based on forms sent by fax, which have to be received, entered in the company's own systems and then forwarded again.

Troubled downloading of the daily key

On July 22nd, 2020 it was reported that on smartphones, for example, the manufacturers Samsung and Huawei (Android operating system), the key comparison "in the background", i.e. automatically without user intervention, sometimes did not work properly and there were therefore no automatic warning notifications . As part of the "battery optimization" by the operating system, i.e. in order to reduce the power consumption of these devices, the app in both the Android and Apple versions did not automatically have the daily key from the Corona system once a day for weeks. Warning app server downloaded . Only when the app was opened by the user himself, the download and then the comparison and information about the risk status and the recommended action take place . The exchange of identifiers with other smartphones necessary to determine the risk was not affected. The federal government confirmed the error in the automatic download from the Corona-Warn-App-Server, but with reference to the undisturbed exchange of the identifiers between neighboring smartphones, the message: "Corona-Warn-App worked at all times". Robin Houben from the RKI assured that the “basic function of the app” was not impaired, whereupon it was inappropriately generalized that the app “works anyway”. Version 1.1.1 was provided for the Android variant of the app to solve the problem. The new item “Prioritized background activity” can be called up under “Settings” and switched on using the slider. However, this is not pointed out to the user. It is also reported that this manual setting does not help in some Android devices, since changes to the background service that cannot be deactivated have sometimes been made. With iPhones, the problem has been resolved from version 1.1.2.

Risk determination impossible

After the recommended update to iOS version 13.6, a "frequent problem" is that the risk determination can no longer be activated because "encounter recordings are not available in your region". These apps are then completely inoperable. Apple promises to work flat out to eliminate the error.

Risk assessment not communicated

It has been known since the beginning of July 2020 that the Google version of the app, through no fault of the user, does not report the result of the risk assessment for significantly more than 24 hours. Instead, the user receives the message "Risk determination not possible" and the recommendation "If the message continues to appear after 24 hours, please contact the hotline or open an issue on Github". On Github, however, this issue ("issue") has been known for more than a month through reports from several users, but has not yet been resolved despite several updates to the app.

Rework

In mid-July 2020, the RKI stated that due to the large amount of feedback from users, in the first month there had already been “very deep insights” into how the app was performing in everyday life - and where there was a need for improvement. The developers worked continuously to analyze error messages that occur while using the app and to fix the problems.

effectiveness

In the latest version of the “Oxford Study” , the authors explain that the “efficacy” of a tracing app is determined by the square of the usage rate in the respective population, multiplied by the probability that the app encounters risk correctly recognizes, multiplied by the extent to which the chain of infection is slowed down by the warning.

In terms of the result, the effectiveness of the app is to be assessed according to the extent to which it fulfills the two goals set for it: on the one hand, to prevent app users from passing on their infection to third parties, on the other hand, to support the health authorities, to clarify the chains of infection and take official measures from this derive.

Preventing infections from warned app users

If a risk encounter is detected, the app users are given recommendations for action that are intended to prevent them from infecting other people in the event of their own infection. In order for the health authorities to be able to assess this, the official documentation of the infection must record whether the infected people were warned by the app. This is not intended. So far, there is no information on whether and to what extent the app had this preventive effect .

Support to the health authorities

The other aim of the app is to make it easier for the health authorities to identify contact persons. Accordingly, a representative of the German Association of Towns and Municipalities estimated before the app was introduced that it would be a useful tool in tracking the contact chains by supplementing the tracking of the health authorities. On the other hand, there was criticism from representatives of the health authorities: They were poorly integrated and were informed too quickly about the functioning of the app. The app also means that more work can be expected instead of relief. This concern was confirmed after the app was introduced by a representative of the Federal Association of Doctors in the Public Health Service : The tasks of the health authorities include health information, education and advice for the population. But the introduction of the Corona warning app brought the health authorities a flood of inquiries relating to medical questions, but also to the technology of the app. That "blew up all dimensions that we have ever had".

At the beginning of July 2020, the Handelsblatt learned from health authorities in Hanover, Hamburg and the Gütersloh hotspot at the time that no person had reported there after being warned by the app. A person reported to the health department in Cologne, but the corona test carried out was negative. Markus Mempel, spokesman for the German District Association , commented that at a time when the number of new infections is low, there should be few alarms from the app. Despite the app, the breaking of infection chains still depends on contact tracking by the health authorities. The app is “not a silver bullet”. However, if the app actually leads to users warned by the app contacting the health system as requested, Gérard Krause estimates that the role of contact person management by the public health service will even increase.

In mid-July 2020, the State Office for Health and Social Affairs in Mecklenburg-Western Pomerania (LAGuS MV) announced that the health authorities in Mecklenburg-Western Pomerania had not yet received any relief. Due to the low number of new infections, there are currently hardly any points of contact with the warning app for the individual health authorities.

At the beginning of August 2020, when there were delays in corona tests at the beginning of the wave of German holidaymakers returning from abroad, the Bavarian State Ministry for Health and Care announced at the request of FDP member Sebastian Körber that there was a deviation from an agreement in Bavaria with the federal government, instead of 650 “contact tracing teams”, only 228.

Authors and responsibilities

The Corona-Warn-App is a system for whose technical, legal, medical and organizational functions, and an ongoing process, for whose coordination, adaptation and continuous improvement numerous organizations contribute and are responsible:

Editor and data protection officer of the app: German Federal Government, represented by the RKI
Ownership of the app (including the source code): SAP SE & Co. KG
Authors of the source code of the app: numerous professionals and volunteers, including SAP, Deutsche Telekom, Fraunhofer-Gesellschaft ; HealthyTogether; Helmholtz Association of German Research Centers including CISPA - Helmholtz Center for Information Security ; RKI; TÜVIT ; more than 7,000 entries from the rest of the IT scene
Authors of the source code of the Exposure Notification Framework interface: Google and Apple, supported by Fraunhofer, among others
Responsible for data protection of the interface to the operating system and the operating system: Google and Apple
Responsible for aspects of infection protection and epidemiology: RKI
Operation and maintenance of part of the technical infrastructure (processor in accordance with Article 28 GDPR): T-Systems International GmbH and SAP Deutschland SE & Co. KG, runtime environment in the Open Telekom Cloud
Operation of the hotline: commercial call center as a subcontractor of T-Systems

privacy

In a comprehensive data protection impact assessment, as required in the General Data Protection Regulation Art. 35, the risks that the processing of personal data entail were assessed.

The risks that arise through the use of third-party technologies are assessed as particularly high: “The fact that the CWA app uses the connectivities and the ENF from Google and Apple represents a considerable risk, which is practically not due to the RKI and cannot be reduced on a technical level. "

Tracking via Google Play Services is particularly criticized for Android devices and a transparent documentation of the interaction of the GAEN framework (Google Apple Exposure Notification) with the Play Services is required.

The authors state that the use of corona tracing apps is still unknown and that the acceptance of restrictions on fundamental rights is “possibly in vain”. They explain that the disadvantages and dangers under data protection law can be justified as long as they are offset by a relatively predominant use of the app. However, the proportionality must be "continuously evaluated" in the event that the underlying circumstances change.

costs

The development costs amounted to around 20 million euros, of which 9.5 million euros go to SAP and up to 7.8 million euros to the Telekom subsidiary T-Systems . By July 10, 2020, 7.5 million euros had been spent on advertising and around 100,000 euros went to security testers. In June it was said that 35 million euros will be spent on advertising. In addition, in the coming years, depending on the demand for “maintenance of the app” at SAP, up to 1.9 million euros and for “operation of the app”, including maintenance, security, network and hotlines, up to almost 43 Million euros will be spent on T-Systems.
The verification hotline operates 24/7 and can be used in German, English and Turkish, while the technical hotline is only manned from 7:00 a.m. to 10:00 p.m. and can be used in German and English. The monthly costs are estimated at around EUR 2.5 million.
When the app was presented on June 16, Timotheus Höttges (CEO of Deutsche Telekom AG) announced that the mobile operators in Germany would not charge their customers for data traffic from the app.
If the app has displayed the warning "Increased risk", since July 9, 2020, in the area of statutory health insurance , contract doctors have been reimbursed EUR 10.00 per patient for the smear without counting the practice budget and laboratory doctors a total of EUR 43.54 .

Opinions and discussion

Federal Commissioner for Data Protection

The Federal Commissioner for Data Protection said it was a “solid impression”, while TÜV Informationstechnik stated that “the app would run reliably and securely without spying on the user. Unauthorized persons could not access any data ”.

Advisory Council on Consumer Issues

In a publication by the German Advisory Council for Consumer Affairs on June 2, 2020, the effectiveness of the decentralized app was questioned with reference to the upcoming introduction of the decentralized app. It depends on several factors:

The use and suitability of smartphones
- An estimated 14 million people in Germany do not use a smartphone (around 19 percent of the population).
- around 20 percent of the smartphones currently in use are technically unsuitable for installing the app.
- In the high-risk group of people over the age of 70, an estimated four million (36 percent) are non-users.
The number of owners of suitable smartphones who
- install the app;
- are ready to have Bluetooth permanently switched on;
- are ready to have their positive test result entered on the server.
The prevalence of current COVID-19 infections: if the spread of infectious COVID-19 cases is low, the effectiveness of the app is reduced. From the beginning of June to mid-July 2020, with some fluctuations, fewer than 500 positive corona tests were officially recorded on average every day. Even if 33 percent of the population actually used the app during this time, the frequency of infection among users of the app would correspond to the average of the population and all infected users reported their infection in the app system, as well as contacts in sufficient proximity and duration to other users the app would only collect and report to users at an average of 50 high-risk contacts. That would be just enough to “learn” from the app system. In contrast to the situation in March and April 2020, there is now the possibility of learning without mistakes having a serious impact on the infection process. Therefore, “the social experiment warning app” should be tackled despite all the uncertainty.

The extent to which the app ultimately achieves the goals set in it will probably only become apparent in a few months after a few corrections and adjustments to further epidemiological findings. The app can therefore currently only serve to gain experience in order to be better prepared for a possible second wave of infections.

Incentives and privileges

At the time when the federal government was still planning to store user data centrally for the app , there were recommendations from politics and business on how the use of the app should be promoted and how it should also be used for fundamentally different purposes: CDU Union parliamentary group Vice Thorsten Frei advocated giving users a tax credit. Axel Voss , legal policy spokesman for the Christian-Democratic EPP Group in the European Parliament, recommended creating “incentives” so that many citizens can get involved in digital contact tracking. App users should be allowed to travel to neighboring countries again and be the first to go back to the restaurant, cinema, theater and swimming pool.

In fact, it became known in mid-August 2020 that an entrepreneur made the installation of the app a condition for economic performance: The operator of a campsite in the North Frisian district of Aurich only grants access to the facility if the app is installed.

Legal clarification

The CDU domestic politician Armin Schuster said that if the app proves itself, but the population “does not participate enough”, the obligation as an option should at least “remain in the quiver as a further political option”. A widespread legal comment is of the opinion that if employees use smartphones for work, employers could order the installation of the Corona warning app to protect their workforce, but it is not possible for employees to actually use the Corona warning app . When using the app, however, employees are obliged to report a positive test result to the employer due to their mutual duty of care.
Against the background of such representations, several organizations recommend or demand that misuse of the app, especially by authorities and companies and to the detriment of consumers or customers, be prohibited through an accompanying or introductory law, for example the Advisory Council on Consumer Issues , which advises the Federal Ministry of Justice DGB , the German Lawyers Association , Amnesty International , Caritas , in connection with the draft law the party Bündnis 90 / Die Grünen and the party Die Linke .

On the other hand, others rejected a law accompanying the app: The President of the Bitkom IT association , Achim Berg, said that in view of clear requirements from the EU General Data Protection Regulation, another law was simply “superfluous for a voluntarily used app that is based on consent ". Federal Minister of Justice Christine Lambrecht also argued: A law is unnecessary, all data protection issues are covered, the GDPR applies.

University study

Scientists from the Technical University of Darmstadt , the Philipps University of Marburg and the JMU Würzburg warned in a publication dated June 9, 2020 that they have demonstrated data protection and security risks in the process used in the Corona Warning app under everyday conditions: The app can accordingly, in the version intended for use in mid-June 2020, they will be misused to create personal movement profiles and possibly to de-anonymize infected people. Contacts can also be simulated and the accuracy of the system impaired. At the time, the authors also pointed out that although the code of the German app had become verifiable through publication, the code from iOS or the proprietary Google Play Services, which created the technical basis for the app, was not. Since mid-July 2020, the ENF code has been freely available to both Google and Apple.

Chaos Computer Club

On April 6, 2020, Linus Neumann from the Chaos Computer Club published ten touchstones for assessing "contact tracing" apps. These would have to withstand the following points: Epidemiological meaning and purpose, voluntariness and freedom from discrimination, fundamental privacy, transparency and verifiability, no central entity that must be trusted, data minimization, anonymity, no development of central movement and contact profiles, unlinkability and unobservability of communication . On April 26th, Neumann welcomed the change from the “central” to the “decentralized” concept for the planned corona tracing app. After knowing the code of the version that has been downloadable since June 16, 2020, Neumann said: "The community has already made many suggestions for improvement that SAP and Telekom have implemented". Some media interpreted this to mean that IT experts and hackers were "satisfied" with this app version.

Further comments

Science and politics pointed out that the app was “not a miracle cure”, but in addition to hygiene measures such as keeping your distance, washing your hands and everyday masks (“AHA rule”), it could help to contain the corona pandemic.

The "Oxford Study"

This is a publication in three versions in which the effects of different measures on the spread of SARS-CoV-2 were simulated . In the German media it is quoted repeatedly from interviews with Lucie Abeler-Dörner, one of the co-authors of the Oxford study, that chains of infection could already be broken if only 15 percent of the population used the app simulated in the study.

In all three versions of the Oxford study, however, legal, epidemiological and organizational assumptions were made that cannot be transferred to German conditions.

In the report published on March 31, 2020 as a pre-print and two weeks later as a pre- peer review by authors mainly from the University of Oxford, simulations are used to calculate the extent to which a Corona app can be successful. However, the epidemiological situation in the simulations is fundamentally different than when the German app was introduced two months later: the British app assumed for the calculations should be seven days before the end of a lockdown with a prevalence of two percent with reproduction values of 3.0 and 3 , 4 start. In addition, the assumptions in the Oxford study are not compatible with German data protection law. The app should collect extensive situational and personal data and store it centrally. The authorities should evaluate the stored data on a personal basis, assign biographical, clinical and laboratory chemical data of the app users and derive personal and collective measures from it. The authors estimate that under these “optimizing” conditions, such an app could prevent a second lockdown if 56 percent of citizens use the app, and delay a new lockdown if the prevalence is one percent if 15 percent of citizens use the app.

In its third version, after a peer review, the Oxford study was published on May 8, 2020, with significant changes. The authors now simulate the course of the early stage of the SARS-CoV-2 pandemic in China with the epidemiological data applicable at the time. They summarize that the epidemic cannot be brought under control by conventional contact tracing due to the infectiousness of the pathogen and the high proportion of infections before symptoms appear (“Given the infectiousness of SARS-CoV-2 and the high proportion of transmissions from presymptomatic individuals, controlling the epidemic by manual contact tracing is infeasible "). However, the German app came into use on a voluntary basis only several months after the epidemic had been contained here by conventional contact tracing contrary to this assessment. The authors recommend restricting the anonymity of users so that the planned app can also give user-related official instructions ("instructions") or food and medication can be ordered via the app for delivery to quarantine. In view of the rapid spread of the pathogen in Europe, an almost total use of the app and an almost perfect compliance with requirements is necessary (“requiring near-universal app usage and near-perfect compliance”).

In its opinion, the German Advisory Council on Consumer Affairs therefore points out that the calculations of this version of the Oxford study are based on numerous assumptions that do not apply to Germany, such as a homogeneous population, a doubling time of infected people of only five instead of (in Germany in May 2020) 184 days and an "instantaneous contact tracing", so that all contact persons receive the app warning on the same day on which the person at risk notices the first symptoms.

Comments on the version before June 2020

Christian Drosten , virologist at the Berlin Charité, said on April 7th, 2020: “If 60 percent of the population were to install such an app and then again about 60 percent of those who were informed that they should stay at home would really close Stay at home, then you could reduce R0 below one. That is amazing. [...] that would actually do a lot more or almost the same as a real lockdown. "

Rena Tangens and Nils Büschke from Digitalcourage published an assessment of the planned contact tracing app based on the PEPP-PT concept on April 8, 2020. In his opinion, the concept is not “anonymous”, but at best pseudonymous. This assessment was based on the false assumption that "potentially endangered people are informed". In reality, however, the app only calls up the anonymized data of infected people from a server in order to then calculate locally on the personal device whether there has been contact with infected people, so that the process is completely anonymous.

Klaus Müller , the head of the Federation of German Consumer Organizations, warned on April 11, 2020, “The use [must] be voluntary, proportionate and limited in time. [...] The Corona crisis should not serve as a gateway to give companies new access to private data. "

On April 14, 2020, the Forum Computer Scientists for Peace and Social Responsibility published a comprehensive data protection impact assessment for the Corona app.

In the ZDFzoom documentation (first broadcast on April 29, 2020) controversial reports were made about the Corona app. In order to record neighboring devices using Bluetooth Low Energy , the app should also be able to run in the background when the smartphone is locked, which was not the case at the time.

Implementation of the decentralized approach

Central approach

On April 15, 2020, the heads of government of the federal and state levels decided to support the PEPP-PT initiative , which wanted to develop software on the basis of which, with the central storage of contact data, various national contact tracing apps in Europe can be created. As part of the leadership team, Chris Boos became known to the public, probably also because he was previously a member of the digital council of the federal government and at the Bilderberg Conference 2019. Several developer groups came together under this umbrella, and competing approaches were also pursued. At first it seemed that, thanks to the support of the federal government, the “central approach” for a German contact tracing app would prevail. When asked at a press conference on April 16, 2020, the federal government wanted to continue to rely on Chris Boos ' project despite the joint effort by Apple and Google .

When this preliminary decision by the federal government became publicly clear, criticism began. In the course of the discussion, the federal government said that the app should provide additional knowledge for epidemiological research.

In response to a written question from Anke Domscheit-Berg on April 20, 2020, it was announced that various alternatives were still being considered (DP-3T, PEPP-PT and the Stop Corona solution from Accenture GmbH used in Austria ).

The two US technology giants Apple and Google insisted on a decentralized storage solution for Corona apps. It will not be shaken. That was important, because 99 percent of all smartphones worldwide use an operating system from Apple or Google. Especially since the radio technology Bluetooth Low Energy does not normally run in the background on Apple smartphones , as it makes sense with this application and with the use of the software currently programmed by Apple, the representatives of the "decentralized approach" got through the definition of Apple and Google , adapting their operating systems for contact tracing apps, powerful supporters.

Switch to the decentralized approach

Technically, the federal government was therefore dependent on a concession from the two companies. On April 24, 2020, however, a spokeswoman for the federal government had confirmed the preference for the central concept of PEPP-PT. On the same day, the Chaos Computer Club, the Gesellschaft für Informatik and other organizations that deal with network policy issues published an open letter to the federal government. It said: “Your preferred concept for the app is not the right way.” On the night of April 26, 2020, the federal government gave in and said in the morning that it now prefers a decentralized approach. They will promote “a decentralized architecture” that “only saves the contacts on the devices and thus creates trust.” A press release dated April 28, 2020 announced the release of the app by the Robert Koch Institute after “completion by Telekom and the SAP “in prospect.

On May 12, 2020, a source code repository was published on GitHub .

The aim of the project is a decentralized solution with data storage locally on the smartphones based on the Privacy-Preserving Contact Tracing Protocol (PPCP) from Apple and Google via Bluetooth. The technology is heavily inspired by the DP-3T and TCN protocols and like these, apps and backend infrastructure will be made completely open source under Apache 2.0 license .

Alternative developments

The Corona Tracing API developed by Google and Apple, the interface between the operating systems and the app published by the RKI, is, like the operating system itself, proprietary and, with the exception of the ENF, non-transparent. To avoid the legal and technical dependency and data protection concerns that result from this, an initiative is under way to develop a free and open source implementation of the PPCP for Android under the name “CoraLibre”. In the next step, an alternative to the RKI's corona warning app should follow, which is compatible with the structures that the RKI app uses.

Huawei is in the process of developing a proprietary corona tracing API for its devices that are not provided with the interface by Google.

literature

Thomas Köllmann: The Corona Warning App - interface between data protection and labor law . In: New journal for labor law . No. 13 , 10 July 2020, p. 831-836 .

Web links

Commons : Corona warning app - collection of images, videos and audio files

Official website
Federal government: Corona warning app
UKW030 The Corona Warning App - Podcast with the programmers of the app

Individual evidence

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↑ Dominik Lauck: Fight against pandemic: This is the problem with the Corona app. In: tagesschau.de. April 29, 2020, accessed May 2, 2020 .

↑ ^a ^b Corona warning app on GitHub

↑ Corona warning app to prevent the spread of coronavirus. Where can I find more information and data on the app? (No longer available online.) In: Bundesregierung.de. May 15, 2020, archived from the original ; accessed on May 20, 2020 .

↑ CoraLibre: Initiative website , as of July 13, 2020, accessed July 13, 2020

↑ CoraLibre: Presence on GitHub , as of July 13, 2020, accessed July 13, 2020

[:Play_Store-1] installation page for Android. In: Google Play . Accessed August 2020 .

[:Apple_Store-2] Preview page for iOS. In: App Store (iOS) . Accessed June 2020 .

[3] Jakob Möller: cwa-app-android. GitHub , August 19, 2020, accessed August 19, 2020 .

[BReg_CWA_FAQ-4] ↑ ^a ^b ^c ^d ^e ^f ^g Support us in the fight against Corona. In: Bundesregierung.de. Retrieved July 5, 2020 .

[RKI_digital_unterbrechen-5] Digitally interrupt chains of infection with the Corona warning app. RKI, July 2020, accessed August 2020 (being updated).

[SAP_technGrundl-6] Juergen Mueller: COVID-19: The technical basis of the Corona-Warn-App in Germany , online May 20, 2020, access June 18, 2020

Corona warning app

The Corona-Warn-App is an app that aims to help track and interrupt chains of SARS-CoV-2 (COVID-19 trigger) infection in Germany.
Basic data
developer	SAP & Deutsche Telekom
Publishing year	2020
Current version	1.2.1 ( Android - Google Play Store) August 12, 2020 1.2.1 ( iOS - Apple Store) August 12, 2020
Current preliminary version	1.3.0-SNAPSHOT-RC6 ( Android ) August 19, 2020
operating system	Android , iOS
category	COVID-19 app
License	Apache license, version 2.0
German speaking	Yes
www.coronawarn.app

Corona warning app

History and objectives

Languages ​​and use in other countries

functionality

Web server

Risk assessment

Report of the positive corona test

Risk assessment

Information and recommendation for action

conditions

Position of the European Parliament

German law

Technical requirements

General

Android

Apple

Expectations and acceptance

Downloads

Distribution to the operating systems

impact

use

Information provided by the editor

Comparison with the Swiss app

Influence on effectiveness

Influencing variables

Biographical and socio-economic barriers

Parameters

Retrieval of the teleTANs

Available positive corona tests

Available day keys

Retrieval of the daily key

Output of warnings

Risk of transmission to the risk person

Calls to the hotlines

Survey

reliability

Recording of the duration and proximity of the contact

Neglecting multiple sub-critical encounters

Gaps in reception

Reliability of test results

Timeliness

Technical problems

Insufficient digital integration

Troubled downloading of the daily key

Risk determination impossible

Risk assessment not communicated

Rework

effectiveness

Preventing infections from warned app users

Support to the health authorities

Authors and responsibilities

privacy

costs

Opinions and discussion

Federal Commissioner for Data Protection

Advisory Council on Consumer Issues

Incentives and privileges

Legal clarification

University study

Chaos Computer Club

Further comments

The "Oxford Study"

Comments on the version before June 2020

Implementation of the decentralized approach

Central approach

Switch to the decentralized approach

Alternative developments

literature

Web links

Individual evidence

Languages and use in other countries