[ampersandy]

What about staying inside with cool/dry air causes these infections? Genuinely curious.

[ma2t]

Recent studies suggest it's not just staying indoors or viruses hanging around longer in cold/dry air. Exposure to cold temperatures may suppress specific immune mechanisms in respiratory tract. See paper out this month, Huang et al "Cold exposure impairs extracellular vesicle swarm–mediated nasal antiviral immunity" https://www.sciencedirect.com/science/article/pii/S009167492...

[timr]

Staying inside should be obvious by now. These pathogens evolved to exploit the fact that people get together in close quarters and breathe together.

Cold/dry air: most respiratory viruses we've looked at survive for longer in cold, dry, dark air.

[version_five]

Sorry I don't have a link but I read few years ago that dry air typical of heated indoor spaces in winter means that virus (or maybe virus + moisture we breath out) stay suspended in the air longer

[valarauko]

Low relative humidity dries out the aerosol droplets faster before they have a chance to settle out of the air.