Warmer weather coincides with more sun, which coincides with higher vitamin D levels, related to immune system function. Sunshine does lots of other good things too.
In colder weather people stay indoors, with more opportunities for sharing infections, and get even less sun.
In colder weather people close windows leading to more retention of infectious agents.
I am sure there are many more. Temperature may be a proxy for something else.
Or it might be “the thing” as Joe Biden might put it. Maybe aerosol droplets evaporate fasted in warm air. In this case turning up the aircon might help.
Also a confounder that was only mentioned briefly in the original post: it also seems like human population in general is concentrated on this climate zone. Can we statistically isolate population density from this analysis?
Consider possible confounders:
Warmer weather coincides with more sun, which coincides with higher vitamin D levels, related to immune system function. Sunshine does lots of other good things too.
In colder weather people stay indoors, with more opportunities for sharing infections, and get even less sun.
In colder weather people close windows leading to more retention of infectious agents.
I am sure there are many more. Temperature may be a proxy for something else.
Or it might be “the thing” as Joe Biden might put it. Maybe aerosol droplets evaporate fasted in warm air. In this case turning up the aircon might help.
Also a confounder that was only mentioned briefly in the original post: it also seems like human population in general is concentrated on this climate zone. Can we statistically isolate population density from this analysis?
The potential confounders you listed are also relevant to very cold places (northern Europe/Canada) and it seems they are currently less affected.