[HollyB]

I thought people got sick in the winter because people congregate indoors and can spread more germs . Not because of the temperature.

[steve86]

I wasn’t addressing epidemiology, only the viability of respiratory viruses. If you want to deactivate viruses you heat to 70°C, not cool them. Cooling them preserves them.

[Wissa]

I thought people got sick in the winter because people congregate indoors and can spread more germs . Not because of the temperature.

There can be a number of factors. Besides the increased exposure that you mentioned, getting chilled is stressful to the body, weakening the immune system. Probably not all that often that happens nowadays though. I think a bigger factor is that we can't get vitamin D from sunlight in the winter, and the vitamin D reserves that we've stored in our fat deposits get depleted as the winter progresses.