Don't get tested on a Friday or Saturday. Here are the percentage of positive tests in Scotland. There's a weekly cycle.

You're twice as likely to test positive on a Friday than on a Sunday. Once a week the lab will have a thorough clean and will bring out new chemicals for testing. I think I know which day they're doing that.

This is a result of a) PCR testing being a difficult test to do with only the tiniest amount of material needed to contaminate results and b) laboratories being under huge pressure to process volumes of tests at speed. Either volume or speed must be compromised to enable quality.

@threadreaderapp unroll

@AlixJoan1 was the hero who spotted this.