4 ms·

I'm not a virologist, but it seems like even in NYC the antibody test was "only" ~20% positive. ~30% if you drill down to certain subgruops: https://www.6sqft.

I'm not a virologist, but it seems like even in NYC the antibody test was "only" ~20% positive. ~30% if you drill down to certain subgruops: https://www.6sqft.com/new-york-covid-antibody-test-preliminary-results/ https://www.6sqft.com/new-york-covid-antibody-test-prelimina... I think it would mean, even in NYC, its current "herd immunity" would reduce the so-called R value by only 20%. That doesn't sound enough to explain the difference between NY and CA.

irq11 6y ago
There have been multiple publications in the last month suggesting that a substantial fraction (i.e. 40% or more) of the population could have some level of cell-mediated immunity to the virus. https://www.sciencemag.org/news/2020/05/t-cells-found-covid-19-patients-bode-well-long-term-immunity https://www.sciencemag.org/news/2020/05/t-cells-found-covid-... https://www.biorxiv.org/content/10.1101/2020.06.29.174888v1 https://www.biorxiv.org/content/10.1101/2020.06.29.174888v1 On top of that, the threshold where growth slows is substantially lower than the “herd immunity threshold” that is naïvely calculated from R0. The flu almost never infects more than 10-15% of the population, despite an R0 of around 1.8, and a corresponding “herd immunity” threshold in the 50% range. A recent Science paper suggested a more reasonable herd immunity threshold of 43% for Sars-CoV2. https://science.sciencemag.org/content/early/2020/06/22/science.abc6810 https://science.sciencemag.org/content/early/2020/06/22/scie... Between the two, it’s not inconceivable that NYC has reached the point where virus transmission is substantially self-limited. It’s not even a remote possibility - it’s likely.
cma 6y ago
If you look at the subgroup of most socially connected people most likely to come into lots of contact with other people, they probably hit really high numbers. And then those "hub" people being immune could have an outsized effect on reducing further spread. I have no idea of he numbers though and if it is playing a large role.

irq11 6y ago

There have been multiple publications in the last month suggesting that a substantial fraction (i.e. 40% or more) of the population could have some level of cell-mediated immunity to the virus. https://www.sciencemag.org/news/2020/05/t-cells-found-covid-19-patients-bode-well-long-term-immunity https://www.sciencemag.org/news/2020/05/t-cells-found-covid-... https://www.biorxiv.org/content/10.1101/2020.06.29.174888v1 https://www.biorxiv.org/content/10.1101/2020.06.29.174888v1 On top of that, the threshold where growth slows is substantially lower than the “herd immunity threshold” that is naïvely calculated from R0. The flu almost never infects more than 10-15% of the population, despite an R0 of around 1.8, and a corresponding “herd immunity” threshold in the 50% range. A recent Science paper suggested a more reasonable herd immunity threshold of 43% for Sars-CoV2. https://science.sciencemag.org/content/early/2020/06/22/science.abc6810 https://science.sciencemag.org/content/early/2020/06/22/scie... Between the two, it’s not inconceivable that NYC has reached the point where virus transmission is substantially self-limited. It’s not even a remote possibility - it’s likely.

cma 6y ago

If you look at the subgroup of most socially connected people most likely to come into lots of contact with other people, they probably hit really high numbers. And then those "hub" people being immune could have an outsized effect on reducing further spread. I have no idea of he numbers though and if it is playing a large role.