Writing up a Long Covid post and noticed this. Several things even taking study here at face value. Putting this here as a ‘preprint’ basically to see if there are counterarguments. And regardless, thanks for the link, it should be considered, but I do not think this constitutes bunk.
One, everyone with a Ct of about 25 or lower got antibodies, so we’re talking about light cases or outright false positives that then didn’t get antibodies. And the spike in cases of Ct~37 is weird enough that I suspect something wrong with the PCRs.
Two, this implies that positive antibody test still means Covid (no false positives, only false negatives) so it would take a VERY large correlation with long Covid to have no correlation show up in the final data—keep in mind that Ct<25 still meant full positives later, so the correlation here can’t be that big.
Three, we’d basically have to assume that virus count isn’t linked to chance of long Covid or this doesn’t make any sense, because all the high virus count cases are getting positives anyway. But lots of virus seems like it would be more likely to lead to long Covid because physics?
Also from the French paper they use this source: https://pubmed.ncbi.nlm.nih.gov/33139419/ which reports tests have high accuracy and has >10x the sample size of the one linked above.
My interpretation of the linked study here is ’sufficiently mild cases sometimes don’t generate antibodies but show up on PCR, and/or PCR tests are getting false positives and we should not take Ct>30 very seriously. E.g. from here.
7. What can CT values tell us? Samples with CT values <32 generally contain sufficient genetic material for WGS and are more likely to contain replication competent virus. Although there are limitations in the use of CT values, they are one factor to consider when evaluating molecular test results and can be useful in assessing the trend in the viral load. If there is high suspicion of a new infection, laboratories may attempt WGS on samples with CT value <32.
Writing up a Long Covid post and noticed this. Several things even taking study here at face value. Putting this here as a ‘preprint’ basically to see if there are counterarguments. And regardless, thanks for the link, it should be considered, but I do not think this constitutes bunk.
One, everyone with a Ct of about 25 or lower got antibodies, so we’re talking about light cases or outright false positives that then didn’t get antibodies. And the spike in cases of Ct~37 is weird enough that I suspect something wrong with the PCRs.
Two, this implies that positive antibody test still means Covid (no false positives, only false negatives) so it would take a VERY large correlation with long Covid to have no correlation show up in the final data—keep in mind that Ct<25 still meant full positives later, so the correlation here can’t be that big.
Three, we’d basically have to assume that virus count isn’t linked to chance of long Covid or this doesn’t make any sense, because all the high virus count cases are getting positives anyway. But lots of virus seems like it would be more likely to lead to long Covid because physics?
Also from the French paper they use this source: https://pubmed.ncbi.nlm.nih.gov/33139419/ which reports tests have high accuracy and has >10x the sample size of the one linked above.
My interpretation of the linked study here is ’sufficiently mild cases sometimes don’t generate antibodies but show up on PCR, and/or PCR tests are getting false positives and we should not take Ct>30 very seriously. E.g. from here.
The bulk of the issues were in CT values >=32.
Anyone have more thoughts?