The Transport Secretary said the app’s sensitivity is under review to make sure it is not catching people unnecessarily. Exposure alerts sent to users of the app in England soared by more than 60 percent in a week, figures show.

       An increase in Covid cases and the upcoming end of social distancing rules have led to fears millions will be contacted and told to quarantine.

       Self-isolation rules will remain even for the fully vaccinated until August 16.

       Mr Shapps said: “Medical experts will advise us on what the level of sensitivity should be relative to where we are.

       “We will follow scientific advice, keep this under review and tweak the app to the circumstances.”

       He urged people not to ignore the app if they are advised to self-isolate or delete it after cases of the dominant Delta variant rose by a third in the past week.