Nice post! Agree on most conclusions except I put more weight on the herd immunity threshold being not much lower than the naive compartment models imply.
Serology data from the 1968 flu pandemic seem to rule out large effects of heterogeneity on the final attack rate. First wave seropositivity was ~35% (mostly 25-50%) with an R0 of ~1.5. R0 increased in the second wave to ~2.5, and seropositivity ended up mostly around 60-70%.
People claiming big heterogeneity impacts seem to have focused on models over empirics. Unfortunately the range of effects implied by different ways of modeling heterogeneity is very wide, with not much to choose between models but actual epidemic data.
Thank you for the dose of empiricism. However, I see that the abstract says they found “little geographic variation in transmissibility” and do not draw any specific conclusions about heterogeneity in individuals (which obviously must exist to some extent).
They suggest that the R0 of the pandemic flu increased from one wave to the next, but there’s considerable overlap in their confidence intervals so it’s not totally clear that’s what happened. Their waves are also a full year each, so some loss of immunity seems plausible. I wonder, too, if heterogeneity among individuals is more extreme when most people are taking precautions (as they are now).
Nice post! Agree on most conclusions except I put more weight on the herd immunity threshold being not much lower than the naive compartment models imply.
Serology data from the 1968 flu pandemic seem to rule out large effects of heterogeneity on the final attack rate. First wave seropositivity was ~35% (mostly 25-50%) with an R0 of ~1.5. R0 increased in the second wave to ~2.5, and seropositivity ended up mostly around 60-70%.
People claiming big heterogeneity impacts seem to have focused on models over empirics. Unfortunately the range of effects implied by different ways of modeling heterogeneity is very wide, with not much to choose between models but actual epidemic data.
Thank you for the dose of empiricism. However, I see that the abstract says they found “little geographic variation in transmissibility” and do not draw any specific conclusions about heterogeneity in individuals (which obviously must exist to some extent).
They suggest that the R0 of the pandemic flu increased from one wave to the next, but there’s considerable overlap in their confidence intervals so it’s not totally clear that’s what happened. Their waves are also a full year each, so some loss of immunity seems plausible. I wonder, too, if heterogeneity among individuals is more extreme when most people are taking precautions (as they are now).