It's just like the flu and colds in some ways. Gather together people in a closed environment with poor ventilation and you get infections. People gather together in closed environments in cold weather. That's why any family with young kids in school gets everything going around.
I don't know if this has any scientific basis, but more ultra-violet light from sunshine and heat that dries things out in the warmer weather also helps.
I'm in Canada and while by comparison we're doing not too bad, even in my rural area things are being locked down again. People are grumbling but are generally accepting it as necessary. Those who were the more vocal deniers in the spring and summer are more or less converted to know this is real or are keeping their mouths shut.
From what I understand those places that are taking precautions are also experiencing a lower incidence of seasonal influenza. The same things that help prevent covid or cooties also works there. I'm actually hoping that mask wearing will get normalized here in the winter. My cotton one actually makes a dandy scarf to keep my face warm.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells