Tests

[Littlebopeep123]

OH has just been telling me that one of his colleagues were telling him about his friend who lives with his girlfriend and her parents.
His friend developed a bit of a cough and so had a test and tested positive. They decided that girlfriend and parents would have a test. Girlfriend negative, mum positive but no symptoms and dad negative.
All live together in three bedroom house so how do two catch it and two dont? Or is the negatives actually positive or the positives actually negative? Or all tests actually correct?

The negatives could easily be false negatives (about 30% of cases are) or the test was taken too early or late. Not everyone will catch a disease even with the same exposure though.

It could be that:

The girlfriend and parents already had it at some point earlier and didn't realise.
The test was inaccurate
They had innate immunity that means they didn't get infected.
They just didn't have enough or the right type of contact to get infected.

From the research, it seems all three are possible, so there's no way to know unless they had antibody tests, which would show if they were in fact infected at some point.

Who knows?

amp.theguardian.com/world/2020/sep/27/uk-market-flooded-by-inadequate-covid-tests-experts-suggest?__twitter_impression=true