England and Wales’ NHS COVID-19 contact tracing app has failed to alert users of potential exposures due to a programming error.

The wrong threshold for exposure was reportedly set on the app. When it should have recognised people as having been in close enough proximity to transmit the virus, it instead recorded that they were too far apart.

This means that many of the ‘phantom notifications’ being sent by the app, which Zühlke UK CEO Wolfgang Emmerich, whose team helped develop NHS COVID-19, recently told Medical Device Network indicated a ‘near-miss’, may have been genuine contacts.