Why it’s easier to catch a cold, the flu or COVID in the winter Low humidity protects viruses and cold temperatures may blunt some immune responses, making viral infections like colds, flu and COVID-19 more likely. Tina Hesman Saey Science News

...researchers have found that viruses that surge in the winter, including influenza viruses and SARS-CoV-2 — the coronavirus that causes COVID-19 — survive best when the relative humidity in the air falls below about 40 percent.

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