Why We're More Likely To Catch a Cold in Winter

Is it easier to catch a cold while it is cold outside? It turns out the answer could very well be yes. Here's the science behind it.

Let's begin by looking at how diseases are spread in the first place. Respiratory diseases, like colds, influenzas, and respiratory syncytial virus, also known as RSV, are mainly transmitted through tiny droplets. These small droplets are called aerosols. When a person infected with the flu, for example, coughs, sneezes, or talks, aerosols will be released into the air and can land on anyone nearby or even be inhaled by those close to the infected. So, when people spend more time indoors, like in the wintertime, these tiny droplets can build up. David Fisman, an epidemiologist at the University of Toronto Dalla Lana School of Public Health, told Science News, "When you're outdoors, you're in the ultimate well-ventilated space." So, what happens when you're indoors? He continued, "When you're in a poorly ventilated space, the air you breathe in is often air that other people have breathed out."

In addition to the closed spaces that most of us are stuck in during the cold months of the year, many scientists believe there are other factors that cause these viruses to be more active in the wintertime. Some scientists also believe that humidity levels may have a role in spreading viruses. Since the viruses travel via fluid, like saliva, the humidity levels can affect the droplets' survival rate. Not only does cold weather help certain viruses travel and survive, but it also impacts the way that humans can ward off potential diseases. A group of scientists researched how the body fended off possible diseases and realized that the immune system uses a diversionary tactic to keep viruses away. However, when it gets colder outside, the immune system cannot create as many diversionary cells as it usually could.

There is still so much left to uncover about the science behind why diseases are more active in the winter months. While scientists are busy working on the answer, we are going to bundle up nice and warm this winter. Stay tuned.