3 ms·

As nice as it would be, seroprevalence studies have ruled out the "basically everyone in New York caught it" theory.

jandrewrogers 6y ago
A substantial percentage of infections are believed to not show up in seroprevalence studies. One of the major areas of research right now is determining how large this population is.
- cma 6y ago
  This study proposes 10:1 instead of 6:1 or so found in New York from seroprevalence. So still not anywhere near a majority getting it even if you adjusted by the difference.
- 0xFFC 6y ago
  > A substantial percentage of infections are believed to not show up in seroprevalence studies What is the reason behind this?
  - tripletao 6y ago
    The thresholds for antibody tests were established using known true negative samples (e.g., blood banked before the pandemic) and known true positive samples (e.g., patients who tested positive by PCR). But patients with worse symptoms are over-represented among people who tested positive by PCR (since they're more likely to seek a test), and patients with worse symptoms will generally have higher levels of antibodies in the blood. So if anything, the sensitivity of the test is probably an overestimate, which would make the number infected an underestimate. I've seen a few papers testing asymptomatic patients (identified by contact tracing or other mass testing), with mixed results. NYC uses an in-house test for which I don't believe any paper exists, so I don't think we can say anything there. The IFR from NYC's serology is higher than most other estimates, which could imply under-ascertainment but could also be real (e.g., because they forced nursing homes to accept positive patients, because they were doing early intubation that we now know is harmful, etc.).
SpicyLemonZest 6y ago
T-cell immunity is known to be a relevant factor, though. It'd be unreasonable to assume it fully plugs the gap, but I think there's gotta be some explanation for why only areas hit hard in April were able to keep cases low over the last few months.
- tonfa 6y ago
  Because the population has been more cautious since then?
  - sadfklsjlkjwt 6y ago
    There's nothing like seeing your friends and family struggling to breath to keep you being careful.
zaroth 6y ago
It’s statistically impossible for literally everyone in NY to catch COVID. What recent studies have shown is that while the naive herd immunity threshold is perhaps around 60% (working backwards from R0 estimates), after you factor in clustering of populations, baseline hygienic improvements, and moderate social distancing, that NY did reach an effective level of herd immunity.
- eloff 6y ago
  I hope so. We'll find out either way.

A substantial percentage of infections are believed to not show up in seroprevalence studies. One of the major areas of research right now is determining how large this population is.

cma 6y ago
This study proposes 10:1 instead of 6:1 or so found in New York from seroprevalence. So still not anywhere near a majority getting it even if you adjusted by the difference.
0xFFC 6y ago
> A substantial percentage of infections are believed to not show up in seroprevalence studies What is the reason behind this?
- tripletao 6y ago
  The thresholds for antibody tests were established using known true negative samples (e.g., blood banked before the pandemic) and known true positive samples (e.g., patients who tested positive by PCR). But patients with worse symptoms are over-represented among people who tested positive by PCR (since they're more likely to seek a test), and patients with worse symptoms will generally have higher levels of antibodies in the blood. So if anything, the sensitivity of the test is probably an overestimate, which would make the number infected an underestimate. I've seen a few papers testing asymptomatic patients (identified by contact tracing or other mass testing), with mixed results. NYC uses an in-house test for which I don't believe any paper exists, so I don't think we can say anything there. The IFR from NYC's serology is higher than most other estimates, which could imply under-ascertainment but could also be real (e.g., because they forced nursing homes to accept positive patients, because they were doing early intubation that we now know is harmful, etc.).

SpicyLemonZest 6y ago

T-cell immunity is known to be a relevant factor, though. It'd be unreasonable to assume it fully plugs the gap, but I think there's gotta be some explanation for why only areas hit hard in April were able to keep cases low over the last few months.

tonfa 6y ago
Because the population has been more cautious since then?
- sadfklsjlkjwt 6y ago
  There's nothing like seeing your friends and family struggling to breath to keep you being careful.

zaroth 6y ago

It’s statistically impossible for literally everyone in NY to catch COVID. What recent studies have shown is that while the naive herd immunity threshold is perhaps around 60% (working backwards from R0 estimates), after you factor in clustering of populations, baseline hygienic improvements, and moderate social distancing, that NY did reach an effective level of herd immunity.

eloff 6y ago
I hope so. We'll find out either way.