04-17-2020, 09:16 AM
I guess what I'm slightly confused about with this study is that they got 50 positive results out of 3,330 tests, for a crude prevalence rate of 1.5%. But nothing I can see in their study parameters excluded people who had previously tested positive for COVID-19, so it's not clear to me that their study is only undetected community spread. If there have been over 1,000 confirmed cases, do we know that none of those individuals participated in that test?
And the study design also may be somewhat unrepresentative. As they say themselves, "bias favoring those with prior COVID-19-like illnesses seeking antibody confirmation are also possible. The overall effect of such biases is hard to ascertain." And thus, they didn't try. So based on their estimated sensitivity, coupled with their demographic weighting, they drew from 50 positive results a prevalence rate as high as 4.16%.
And the study design also may be somewhat unrepresentative. As they say themselves, "bias favoring those with prior COVID-19-like illnesses seeking antibody confirmation are also possible. The overall effect of such biases is hard to ascertain." And thus, they didn't try. So based on their estimated sensitivity, coupled with their demographic weighting, they drew from 50 positive results a prevalence rate as high as 4.16%.