Why are colds more common in winter? Scientists find the answer

Scientists have made a breakthrough in the scientific community by discovering why people are more likely to get a cold during winter. 

In a study published on Tuesday in the Journal of Allergy and Clinical Immunology, a team of scientists found that cold air weakens the body’s immune response. One of the areas that are particularly vulnerable to cold air is the nose, one of the places where viruses first come in contact with the body. 

“Cold air is associated with increased viral infection because you’ve essentially lost half of your immunity just by that small drop in temperature,” said rhinologist Dr. Benjamin Bleier, director of otolaryngology at Massachusetts Eye and Ear and an associate professor at Harvard Medical School in Boston, who co-authored the study.

As part of the study, Bleier and his team exposed four participants to 15 minutes of 40-degree Fahrenheit temperatures. They then measured the state inside of their nose to examine how it reacted to the temperature change. 

The study found that a drop of 9 degrees Fahrenheit (5 degrees Celsius) inside the nose kills almost 50% of the billions of virus and bacteria-fighting cells that live in our nostrils. Usually, when a virus or a bacteria enters the nose, it is detected by these cells before being able to enter the body, thereby stopping the invading germ. 

The results of the study help explain why the common cold is more common in the colder months of the year, which are referred to as the flu season. 

“This is the first time that we have a biologic, molecular explanation regarding one factor of our innate immune response that appears to be limited by colder temperatures,” rhinologist and Stanford University School of Medicine professor Dr. Zara Patel, who was not involved in the study, told CNN.