Thread by @BillHanage

The UK is going to be making free rapid tests available to everyone. As you might imagine, I approve. However it should be remembered rapid tests are most effective when combined with other things. Short thread 1/n
nytimes.com/2021/04/05/wor…

For a start, for tests to be useful they have to be used! It is not obvious to me that there is any incentive for that in the proposal. If people suspect they are infected, but don't want the risk of having to isolate, they're not likely to take a test 2/n

Then there's the perennial question of what happens in the event of a +ve test? If people actually isolate that's great, but that's not been universally the case in the pandemic so far, putting it mildly. Hopefully their behavior would change enough to make a difference 3/n

Which brings us to the question of support. People isolating need sick pay! Their contacts need to be encourage to test! Effective pandemic response needs all these things! 4/n

We should also encourage use among people who have recovered from infection. While reinfections are rare, they are expected to get more common as immunity wanes, and are almost certainly more likely with some variants 5/n

Likewise vaccinated individuals. The much-maligned AZ shot has clear efficacy against serious illness, but breakthrough infections are possible, even though it is not clear how likely they would be to transmit 6/n

Which brings me to the whole question of 'Covid status'. I can see all sorts of problems with the approach outlined in the article, but others are better placed to address those concerns, I think 7/n

I will say that for ages, I've argued that if you wanted to open eg movie theaters with minimal transmission risk, you could do it if you required a -ve rapid test before admission, and then everyone wore masks. The latter would mitigate transmission from any rare false -ves 8/n

Which brings me to the close. Yes more use of rapid tests is good, but there has never been a silver bullet. Interventions work in combination, and here we need to encourage uptake, ensure and support isolation, and continue to vaccinate. 9/end