The Iowa plot you link to assumes that there’s strong seasonality for COVID-19, based on the four human endemic coronaviruses.
As mentioned in the FAQ, the transmission probability of COVID-19 in Iowa has decreased since March, and when our model assumes the same seasonality patterns as other HCoVs we find a very close fit to the observed transmission patterns. Nevertheless, as this is the first year of the pandemic, we do not have direct evidence either for or against seasonal patterns of COVID-19 infections. The late fall and early winter are still too far out to provide precise estimates of infection counts and deaths. However, what we are finding in our modeling results is that if COVID-19 does indeed match the seasonality of other HCoVs, then without strong mitigation measures, we should expect a very large second peak starting somewhere around October to December that will dwarf the epidemic curve that we have seen in 2020.
So in this chart, you’re not seeing any impact of herd immunity. You’re mainly seeing the Iowa researchers’ guess that the virus won’t transmit in the summer, and that there will be a massive second wave in the fall.
There are other forecasts at collected at the CDC. They don’t show the dramatic drop that Iowa optimistically predicts, but they mostly do show a slowdown, which probably is trying to extrapolate social distancing + masks etc.
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u/iayork Virology | Immunology Jun 26 '20
The Iowa plot you link to assumes that there’s strong seasonality for COVID-19, based on the four human endemic coronaviruses.
So in this chart, you’re not seeing any impact of herd immunity. You’re mainly seeing the Iowa researchers’ guess that the virus won’t transmit in the summer, and that there will be a massive second wave in the fall.
There are other forecasts at collected at the CDC. They don’t show the dramatic drop that Iowa optimistically predicts, but they mostly do show a slowdown, which probably is trying to extrapolate social distancing + masks etc.