Quote Originally Posted by noel View Post

Clearly false negatives are more alarming, because it results in many people who have covid and are infectious being told they're fine and to go back to work/school etc.
I've thought that myself too. In some cases people are tested again. Look half way down this under the heading The Number of People Tested. One of the reasons it gives for people being tested more than once is:

"individuals with early symptoms who test negative, develop more symptoms and are retested and found to be positive"

https://www.gov.uk/government/public...thodology-note

But I imagine there will be many others who aren't tested again. If everybody was tested twice then the chances of a false negative would be only 4% assuming the false negative rate of one test is 20%. But I would think there is not the capacity to do that at the moment.