Rapid Covid testing in England may be scaled back over false positives – The Guardian

Senior government officials have raised “urgent” concerns about the mass expansion of rapid coronavirus testing, estimating that as few as 2% to 10% of positive results may be accurate in places with low Covid rates, such as London.

…However, leaked emails seen by the Guardian show that senior officials are now considering scaling back the widespread testing of people without symptoms, due to a growing number of false positives.

…On 9 April, the day everyone in England was able to order twice-weekly lateral flow device (LFD) tests, Dyson wrote: “As of today, someone who gets a positive LFD result in (say) London has at best a 25% chance of it being a true positive, but if it is a self-reported test potentially as low as 10% (on an optimistic assumption about specificity) or as low as 2% (on a more pessimistic assumption).”