I was unaware at the high rate of false negative tests, with one study in the BMJ citing a 25% false negative rate in those who self test. This means 1 in 4 people who are positive will test negative. Eep. These people are likely not self isolating, especially if their symptoms are mild and they convince themselves 'it's just a cold'.
I only looked into it as my DH got symptoms earlier in the week and tested positive (he is an essential worker). I then developed symptoms so got a test and was surprised when it was negative. I re-rested the next day and, sure enough, I am positive.
I feel like this should be more widely known and those with symptoms who get a negative test should perhaps be told to re-test 48 hours later (or something like that)?
As an aside, I'm feeling pretty good but poor DH has an awful cough, fever, vomiting and (TMI warning) watery diarrhoea. Here's to hoping it passes quickly.