Regarding percent-positive (positivity) numbers, how do you guys think antibody/serology tests should be calculated?
I read a hit piece from May critical of the way Georgia was figuring their positivity numbers. Though their goal was to make it look like Georgia was cooking the books I came out with the opposite understanding: the authors were clearly ignoring key details to paint the wrong picture.
See, the WHO recommends a positivity rate below 5% before reopening. Though I've seen people criticize states for lowering their positivity rates with more testing, that's the entire point of the WHO's recommendation: To increase visibility and know that the infection rate in the general population is even lower than that (considering positivity is skewed higher from testing probable cases).
So here's where they claim that Georgia is cooking the books:
Georgia doesn't count positive serology tests toward the positivity numbers but does count the negative ones. Supposedly, this gives GA up to 3% lower positivity. OMG!
Well, think about that for a second. You obviously can't count positive serology tests for a true positivity rate since the rate is supposed to measure active cases and a serology test will still be positive after a patient has recovered (hopefully forever). A negative serology test is almost equivalent to a negative PCR test, though it does take a little longer for the body to create antibodies. Counting them as negative tests for the positivity calculations sounds like it would skew the rate down... until you consider that everyone who tests positive will then get a PCR test to see if the infection is still active. Unless they still count it as two tests for the positivity calculation, this will keep the rate balanced and accurate.
Am I missing something here?
This was the article:
The WHO has said in countries with expansive testing, the range for positivity is between 3-12%. Which states are testing enough to meet this goal?
coronavirus.jhu.edu