Why Do People Get Sick When the Seasons Change?

The weather shifts, and it's like clockwork: you update your wardrobe, alter your thermostat, sip that trendy seasonal drink everyone's talking about, and all of a sudden, you're sick. Why does a new season bring coughs and sniffles with it? The answer is pretty simple: Viruses love cool weather.

Watch: Why Do People Get Sick When the Seasons Change?

To Everything, There Is a Season

It may seem like the same illness crops up every time the weather changes, but in fact, the culprit behind your cough varies throughout the year. When winter turns to spring and when summer turns to fall, cold viruses thrive. The two main viruses behind the common cold are rhinovirus and coronavirus, and they proliferate in the cool weather that occurs during those seasonal shifts.

In winter, however, you're more likely to catch the flu. The way the influenza virus is built helps it multiply and spread most effectively when the air is cold and dry. In 2008, researchers published a study in Nature Chemical Biology that found that at temperatures slightly above freezing, the virus maintains a gel-like outer coating that helps it stand up to the elements and travel from person to person. That coating begins to melt at around 72 degrees Fahrenheit (22 degrees Celsius). That makes sense since the coating needs to melt in your body for the virus to infect a living cell, but it also means the virus is less protected in the open air when the weather is warmer.

With both influenza and the common cold, once you've caught a certain strain once, you're generally immune from it for the rest of the season — just hope there aren't a lot of different strains going around.

What about when spring turns to summer? That's something completely different. The new types of pollen and other allergens that fill the air when summer hits can give you a stuffy nose and other respiratory problems. That itself can lead to illness, however, since irritated lungs and nasal passages are more susceptible to infection.

Colds, Colds, Go Away

As for whether you can catch a cold from cold weather itself, that's a myth. It's all the circumstances surrounding cold weather — dry air irritating your mucus membranes and more time spent inside putting you in contact with people who may be sick — that lead to illness. To protect yourself, make sure to wash your hands frequently, get plenty of sleep and exercise, and get a flu shot every year.

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Find out what it's like to protect the world from deadly diseases in "Level 4: Virus Hunters of the CDC - Tracking Ebola and the World's Deadliest Viruses" by Joseph B. McCormick, Susan Fisher-Hoch, and Leslie Alan Horvitz. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Ashley Hamer September 17, 2017

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