Why do so many people get sick in winter?

Hook

Why and how do so many people get sick in winter? Cold and flu season isn't just bad luck. Several things stack up when the weather turns cold.

Indoors

First, we spend more time indoors, close together, with the windows shut. That makes it easier for germs to pass from person to person.

Dry

Second, winter air is dry, especially with the heat running. Many respiratory viruses spread more easily when the air is cold and dry.

Cilia

Third, dry air may weaken your defenses. Your airways are lined with tiny hairs called cilia that sweep out mucus and germs.

Study

In a Yale study in mice, low humidity slowed that sweeping, made it harder for airway cells to repair damage, and weakened an early immune alarm system.

Sun

Shorter days mean less sunlight too, and scientists are still studying how that affects our immune systems.

Help

That's why health agencies push hand washing, staying home when you're sick, and seasonal vaccines, right when winter starts.

Close

So winter sickness comes from crowded rooms, dry air and weaker airway defenses all at once. ThatsWhyHow.