ONS just announced weekly infection rate in secondary school aged children is 0.43%.
Yesterday Test-and-Trace data showed 0.047% of LFTs were positive.
How can we get an estimate of the sensitivity of LFTs from this? I’ve come up with sensitivity=10%
Here are my workings
Yesterday Test-and-Trace data showed 0.047% of LFTs were positive.
How can we get an estimate of the sensitivity of LFTs from this? I’ve come up with sensitivity=10%
Here are my workings
Three issues
#1 0.047% will include LFT false positives – 0.03% according to DHSC, so 0.017% will be LFT true positives.
#2 0.43% will include PCR false positives – lets go for 1 in 1000 (probably less) to be conservative. So 0.33% will be true cases
#1 0.047% will include LFT false positives – 0.03% according to DHSC, so 0.017% will be LFT true positives.
#2 0.43% will include PCR false positives – lets go for 1 in 1000 (probably less) to be conservative. So 0.33% will be true cases
#3 ONS data are based on number of children, LFT on number of tests. If assume two tests per week (but only ever one positive per child) then double the rate to 0.034%
So sensitivity seems to be about 0.034/0.33 = 10%
Anybody else want to present a version of these figures?
So sensitivity seems to be about 0.034/0.33 = 10%
Anybody else want to present a version of these figures?
I guess we probably also need to adjust for the asymp / symp spread (not so sure about this as LFTs are claimed to detect the infection before symptoms). If we presume 50% in children are asymptomatic this could double to 20%. Still not thrilling.
The thought that this is probably the best data we have on the sensitivity of Innova in children though is rather terrifying.
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