Your immune system underperforms when the body temperature goes down. It is not contact with people, the weather affects your immune system too.

> During cold season we stay indoors more which increases our likelihood of being exposed to other people that are sick.

For most people this is not really true nowdays. We work in the same offices and use the same kind of transport when going to the office. We shop in the same stores.

The seasonal lifestyle change is fairly miniscule.