Alongside privacy concerns and low usage rates, the incompatibility of coronavirus tracing apps across different countries has been identified as a potential weakness of the technology. For example, if somebody travels from France to Germany and is diagnosed with Covid-19 in Berlin, a warning cannot be sent to his or her contacts through the French system.
The patchwork nature of the technology's rollout is also a major issue in the United States which is not developing a single national app to identify infection chains and trace contacts. Rather, the decision is being left to individual states who have been given the choice to participate in a major partnership by Apple and Google who plan to build the technology into their operating systems.
The effort was announced by both companies on April 10 and according to research from website 9 to 5 Mac, only four U.S. states said they were participating in it as of July 13. On that date, no state had successfully released a contact tracing app and 17 said they would not participate while the rest provided no response regarding their status.