Why do we seem to get sick more often in winter?

BOSTON - Cold and flu season is upon us, but germs that cause colds are in the air year-round. So, why do we seem to get sick more in winter?

We've always thought that people were more likely to get sick in the wintertime because the cold weather forces us inside where we're more likely to exchange germs. But the fault may rest instead in the nose, which is one of the first points of contact between the outside environment and inside the body.

Researchers at Harvard Medical School and Mass Eye and Ear have newly discovered an immune response inside the nose that fights off viruses responsible for upper respiratory infections, like the common cold, the flu, and COVID-19.

But reducing the temperature in the nose by as little as nine degrees cut its germ-fighting response by almost half.

So now they want to figure out how to bolster the immune response, with a nasal spray, for example, to reduce the risk of infection as temperatures drop.