[EvaH (OP)]

James asks:

Why do the lateral flow tests require using a rather unpleasant throat/nasal swab? Why won't spitting saliva into the buffered solution work in the test strips? What work has been done on C-19 positive patients using this test and what were the conclusions? FYI I used the home kit using just my saliva and I got exactly the same negative result as using a swab. Would I get a positive result if I was infected with C-19?

What do you think?

[Bored chemist]

Why do the lateral flow tests require using a rather unpleasant throat/nasal swab?

Because that's where the virus hangs out.

[set fair]

They would be useful if they retailed for under a fiver. Michael Mina said they could be made for $4. I don't know whether he had his own agenda or the current price is a scam. As they are less sensitive, they miss infections right at the beginning but probably spot intections by the time a person becomes infectious- the problem being that a person could become infectious between tests.

They would be a good tool if they were cheap enough to use every day. At twice a week (as available free in the UK) they could perhaps reduce spread by a half which woulld be a very useful tool, but... that's only could, because lots of people would change their behavior after a negative test.

The promised spit and go  / lick a stick tests have not materialised. My guess is that if they were a goer, then the Chines would be seling them.