As a pediatrician, I used to scoff at the “wives’ tale” that grandmothers told their children and grandchildren when they went outside. “Wear a hat so you don’t get sick!” they would exhort us. When my patients asked why their kids got sick more frequently during the winter, I told them what I had learned. The reason that upper respiratory tract infections rise during the winter months was probably due to the fact that people spend more time indoors in closer contact with others.
A new study released by Harvard Medical School shows us doctors that we were wrong and that, surprise, grandmothers were right all along.
Cold air does, in fact, affect the number of head colds we get in the winter. Until their study, no one really understood the body’s immune response in the nose to typical upper respiratory infection viruses.
According to The new study, published Dec. 6 in the Journal of Allergy and Clinical Immunology, when a virus enters the nose (either through the air or by touch) it lands in the front of the nose. The nose alerts the cells nearby that a virus has hit. Then, the cells produce millions of small vesicles called extracellular vesicles or EV’s. These EV’s swarm to the front of the nose, attacking the viruses. They also grab bacteria fighting proteins and shuttle them to the back of the nose to protect those cells. This keeps the virus from going farther in the nose and moving into the bloodstream.
But the EV’s do more. They have the ability to “grab” hold of the viruses themselves and dump them into nasal mucus, in a sense deflecting them from going to the back of the nose. The whole process is extraordinary when you think about it.
Here’s where cold air comes in. During the winter, when the temperature drops, the temperature inside the nose drops too. The study shows that when they are cold, the cells inside the nose are unable to release as many EV’s by a whopping 42%. With fewer EV’s, the nasal cells aren’t able to fight off the viruses and bacteria as effectively. Also (not to get too technical) but the proteins in the EV’s are less effective in the cold. So, the immune system inside the nose takes a double hit.
And that’s where Grandma comes in (I love this part because I am a grandmother and now-perhaps-my own kids will listen to me.) She knew that cold temperatures lead to head colds that also lead to ear infections. “Put on a hat and keep your ears covered!” she would say. Would kids listen? Usually not.