The application was already available in the App stores of Google and Apple during the night. The download is to be voluntary for all citizens to make it easier to track infections with the help of smartphones. The government is promoting widespread use and promises a high level of data protection. It rejected demands for a law. The doctors support the new app.

The president of the German Medical Association, Klaus Reinhardt, told the German Press Agency: "This is a very sensible instrument". The app is a simple way to detect chains of infection. "However, it also enables personal precautions to be taken - by allowing you to be tested when a warning message is issued." Of course, the app only works if you get as many people as possible to participate. "It would work even better if the system could be made workable across borders in Europe."

The app is to be presented in the morning by the head of the Chancellor's Office, Helge Braun (CDU), several ministers, the Robert Koch Institute, and the commissioned companies SAP and Telekom. It can measure whether mobile phone users have come closer than about two meters over a longer period of time. If a user has tested positive and has shared this in the app, it reports to other users that they have been near an infected person. Contact data is not - as initially intended - stored centrally, but only on the smartphones. The development costs amount to around 20 million euros.

Users were able to download the app onto their smartphones as early as Monday night. In Google's App Store, it was available shortly after 2 a.m., while Apple's took a little longer. Users complained on social media about delays in the availability of the app and problems with downloading. In less than an hour, the teething problems seemed to have been overcome.

The head of the Techniker Krankenkasse health insurance company, Jens Baas, called the app a useful building block in the fight against the spread of the virus. "It makes perfect sense to use the opportunities offered by digitalisation in the fight against Corona," he told the German Press Agency. However, he also said that the app could not work miracles, and of course it did not replace rules of distance or hygiene. A longer development time is always better than badly working rush jobs, as experiences from other countries have shown. Baas was also critical of the role of Apple and Google. "The healthcare system must not be allowed to fall into a dependency trap of the large US corporations - especially when it comes to the handling and use of data."

Secretary of the Chancellor's Office Helge Braun swore by the security of the program. "This app is as secure as it can be", the CDU politician told the news portal "t-online.de". The source code has been disclosed, he said, and a higher level of transparency could "hardly be achieved". Braun confirmed the promise of the Federal Government that the use of the app would remain voluntary: "There is no compulsion to install the app. I expressly rule out a law that forces Germans to download the Corona app. We will stick to the voluntary model."

The SPD health expert Karl Lauterbach assured that the use is harmless from the point of view of data protection: "Nobody is controlled", he told the "Passauer Neue Presse". "Only numerical codes will be exchanged. From these numbers, no one can draw conclusions about the person. The whole process is anonymous." He promised himself "no miracles, but a lot in the fight against the virus.“

The government rejected demands from the opposition to put voluntary and privacy regulations in a separate law. Health Minister Jens Spahn (CDU), for example, argued that the basic data protection regulation would regulate everything necessary.

The consumer centers insist that the app remains voluntary. Employers, restaurants and public authorities should not be allowed to define the use of the app as a prerequisite for access. Federal Minister of Justice Christine Lambrecht told the newspapers of the Funke media group (Tuesday): "I am convinced that there is a broad social consensus that no one should be disadvantaged who - for whatever reason - does not use the app.“

The Deutsche Stiftung Patientenschutz (German Foundation for Patient Protection) demanded that employees in nursing homes, hospitals and medical practices in particular be sensitised to participate. Minister of Justice Lambrecht told the Funke newspapers that in her view the warning app was to be recommended for children with smartphones just as much as for adults - but that each family had to judge for itself.

The German Association of Cities and Towns appealed to users of the app to contact the local health authority if the app shows them a warning: "This way they can support efficient and speedy work by the health authorities," Helmut Dedy, CEO of the Funke media group, told the newspapers.