Had lecture / update today on testing from the infection and virology leads today. Lot of it was technical but underlined the dangerous nature of SARS CoV 2 as a very successful pathogen which is still out there. Needs hunting down with testing, testing, testing carried out by trained swab people with fast turn around.
The Roche test we use was evaluated on about 2000 very old stored blood samples (way pre covid) to test for false positives. After 29 positive tests on known people who have had COVID was licensed and bought by the UK. Background positive tests around here generally 10% and in London hospital workers 47% so all the lecturers would say was they expect the hospital staff to be between 10% and 47%.