Thank you for this! I have a few thoughts about antigen tests.
1: I’d recommend the BinaxNOW as the “standard” home antigen test in the US. Broadly speaking it’s better studied, more accurate, cheaper, and more widely available than the others. Regarding data...
2: I think the best current source of general data on home antigen tests is this meta analysis from September. The results from multiple papers over the last year have been pretty consistent, but this adds a little more power to the numbers. They come up with:
Overall: sensitivity 68%, specificity 99-10%.
Sensitivity for symptomatic individuals: 72%.
Sensitivity for asymptomatic individuals: 52%
Sensitivity for Ct < 25: 94%, Ct > 3: 30%.
(I’ll be writing more about these results in a bit, but the short version is that this strongly supports the belief that test sensitivity depends strongly on viral load and will be highest during peak infectivity).
3: Two additional excellent papers are this one for subgroup analysis and this one for subgroup analysis and discussion of how user error affects accuracy.
4: Related to the above: accuracy seems strongly correlated with viral load, which strongly suggests multiple tests on the same individual at the same time would be highly correlated.
Thanks for linking the meta-analysis and the other papers; will read (and possibly update the post afterwards)! I especially appreciate that the meta-analysis includes studies of BinaxNOW, something I’d been looking for.
Sensitivity for Ct < 25: 94%, Ct > 3: 30%. (I’ll be writing more about these results in a bit, but the short version is that this strongly supports the belief that test sensitivity depends strongly on viral load and will be highest during peak infectivity).
Nice, I’d been hearing/reading about using cycle count to determine how much a test’s results track infectiousness, and that’s really to see the results so starkly supporting that. Looking forward to your writeup!
Thank you for this! I have a few thoughts about antigen tests.
1: I’d recommend the BinaxNOW as the “standard” home antigen test in the US. Broadly speaking it’s better studied, more accurate, cheaper, and more widely available than the others. Regarding data...
2: I think the best current source of general data on home antigen tests is this meta analysis from September. The results from multiple papers over the last year have been pretty consistent, but this adds a little more power to the numbers. They come up with:
Overall: sensitivity 68%, specificity 99-10%. Sensitivity for symptomatic individuals: 72%. Sensitivity for asymptomatic individuals: 52%
Sensitivity for Ct < 25: 94%, Ct > 3: 30%. (I’ll be writing more about these results in a bit, but the short version is that this strongly supports the belief that test sensitivity depends strongly on viral load and will be highest during peak infectivity).
3: Two additional excellent papers are this one for subgroup analysis and this one for subgroup analysis and discussion of how user error affects accuracy.
4: Related to the above: accuracy seems strongly correlated with viral load, which strongly suggests multiple tests on the same individual at the same time would be highly correlated.
Thanks for linking the meta-analysis and the other papers; will read (and possibly update the post afterwards)! I especially appreciate that the meta-analysis includes studies of BinaxNOW, something I’d been looking for.
Nice, I’d been hearing/reading about using cycle count to determine how much a test’s results track infectiousness, and that’s really to see the results so starkly supporting that. Looking forward to your writeup!