QUICK THREAD ON LATERAL FLOW DEVICE (LFD) TESTS:

LFD tests are mainly used for testing people without symptoms and PCR tests are used for those with (new) symptoms.

LFD tests now outnumber PCR tests every week. 1/4

Unsurprisingly positivity rates for PCR tests are much higher than for LFD tests. Reassuringly positivity rates are coming down in both cohorts.

BUT if we are relying more on more on LFD tests then we *must* use them carefully! 2/4

Firstly, they should NEVER be used as a "green light" to indicate no infection - only as a "red light" to indicate that you've got Covid and should isolate.

Do a confirmatory PCR for positive LFDs to minimise false positives & ENSURE support for isolation! 3/4

this messaging at the moment is the wrong way round and dangerous as pointed out by @ReicherStephen https://twitter.com/ReicherStephen/status/1361961670944423937?s=20.

He also highlighted the importance of supported isolation here https://twitter.com/ReicherStephen/status/1362068812464590850?s=20 4/4

PS I do think that used very carefully with proper confirmatory testing & support for isolation, they could be a valuable public health tool in some high traffic settings.