Software bungle meant NHS Covid app failed to warn users to self-isolate | News | The Sunday Times: The%20%u201Cworld-beating%u201D%20NHS%20Covid%20app%2C%20downloaded%20by%2019%20million%20people%2C%20has%20systematically%20failed%20to%20send%20alerts%20telling%20people%20to%20self-isolate%20after%20they%20came%20into%20contact%20with%20infected%20people.