The DHSC said it was updating the app on Tuesday so that users who received the alert would receive a second message telling them they do not need to self-isolate.
A DHSC spokesman said: “NHS Covid-19 app users only need to self-isolate if they get a notification directly from the app advising them to do so.”
The app uses the Bluetooth connections on users’ smartphones to record when they come into close contact with each other and then alerts people when a recorded contact tests positive for Covid-19.
When people get such a notification it will read: “The app has detected that you have been in contact with someone who has coronavirus. Please stay at home and self-isolate to keep yourself and others safe.”
Following the latest app glitch, Paul Hunter, a professor of health protection at the University of East Anglia and an adviser to the World Health Organisation, warned the app could be doing ‘more harm than good’ if it was causing confusion over when people were to self-isolate.
He said reports the app had only issued one alert based on QR codes so outbreaks can be traced to specific shops and venues, also cast doubt on its effectiveness.
He said: “If it’s not telling people the right information and not collecting information in a way that enables clusters to be reported and detected to Public Health England then it could well be doing more harm than good.”