Can anyone advise? My BIL is on day 11 of covid, feels fine but is still positive on lateral flow. He is due to fly back home to US on Wednesday which will be day 16. He will need to go to a test centre to have an observed lateral flow on Tuesday (day 15). What is going to happen if he is still positive on lateral flow? He has an email with his positive PCR result from day 1. Has this happened to anyone before? Is there a 'fit to fly' exemption he can get somehow? Thanks