In April, Coda Story’s Eduard Saakashvili wrote about the privacy debate in Germany, after the German government proposed mass data collection to trace the spread of Covid-19.

Last month, Germany released a coronavirus tracing app that has eased the concerns of digital rights activists and the privacy-sensitive German public. 

Released on June 16, the “Corona-Warn-App” uses Bluetooth to detect and contact people who may have been exposed to someone who has contracted the coronavirus. Germany initially pursued a centralized approach — in which anonymized personal data is stored on a central server accessible by the government — then ceded to privacy concerns and pivoted to a decentralized version, in which data is stored on users’ phones.

Beyond decentralization, the app is open source, with 100% of its code published online and a platform for people to comment, ask questions, and make suggestions. Germany’s Chaos Computer Club — Europe’s largest association of hackers, which often campaigns against surveillance technology — has signaled approval, praising the commitment to transparency shown by the German app’s developers. 

Public health authorities say that digital contact tracing can slow the spread of the virus. A study by the University of Oxford found that tracing apps start working when 15 percent of a population uses them. Figures released this week show that nearly 19 percent of the German population has downloaded the app, a strong start in a country where almost half of the population said they would not download a tracking app, according to a survey by the public broadcast group ARD. 

But the 15.8 million downloads are not necessarily indicative of proper use. 

“Exceeding 15 percent of the population seems promising,” said Melyssa Eigen, a researcher at the Berkman Klein Center for Internet & Society at Harvard University. “But the app is completely voluntary. It’s voluntary to download and voluntary to share that you’ve been infected.”

Eigen says it is likely that some users download the app only to receive warnings about other people. 

“If you become infected, there’s nothing forcing you to share that information,” she said. That’s one of the downsides to a decentralized app. In a centralized approach, the government could intervene based on a person’s contact list. 

“There is a trade-off between privacy and efficiency.” 

For those who cannot avoid crowded situations — people who live or work in densely populated areas — the app may be less effective in preventing the spread of the virus, as it merely acts as a warning. But, overall, the positive reception to its launch could lead to more testing and lower case numbers. 

“It’s pretty impressive that in a country where people are really into their digital rights and fear government surveillance that it’s even been downloaded as much as it has,” Eigen said.