[viking1066]

Sorry I can't find the article, perhaps drowned in covid articles however:

There is a well known research paper from years ago showing that both exposure to cold temperatures and exposure to cold virus could cause cold symptoms, if I recollect right 30% probability when subjects were intentionally exposed to virus, 10% when exposed to cold temperatures. I don't recall the control group results.

This is consistent with covid appearing as an outbreak out of nowhere.