Those who are asymptomatic are having the "lateral flow" test. I have had a look around to try and find its false negative rate, and the commonest figure seemed to be 30%.
There is this, from the BMJ: " A preliminary evaluation from Porton Down and Oxford University9 throws little light on its performance in asymptomatic people or in the field. It suggests the test misses between one in two and one in four cases."







