Everyone knows that colds, flu and other similar illnesses increase during the winter months. Now science has figured out why this happens.
According to researchers from Harvard Medical School and Northeastern University, an immune response unknown until a few years ago that occurs inside the nose and wards off bacteria may not work as well against viruses at colder temperatures.
Their findings were published recently in the Journal of Allergy and Clinical Immunology, a medical journal of the American Academy of Allergy, Asthma, and Immunology.
Many pathogenic pathogens enter the body through the nose. Cells near the front of the nose that detect the presence of such pathogens release billions of fluid-filled sacs – called extracellular vesicles – into the mucus of the nose. The vesicles then attack the pathogens.
However, cold air can interfere with this immune response. Researchers took healthy volunteers from a room with a temperature of 74 degrees Fahrenheit to an environment with a temperature of around 40 degrees.
After about 15 minutes, the temperature inside the volunteers’ noses dropped about 9 degrees. When this same lower temperature was applied to nasal tissue samples, it was found that the number of secreted extracellular vesicles dropped by almost 42% after exposure to colder air.
In a summary Of the study results, Benjamin Bleier – associate professor of otolaryngology at Mass Eye and Ear and lead author of the study – says:
“Conventionally, cold and flu season was thought to occur in the colder months because people are more stuck indoors where airborne viruses could spread more easily. Our study, however, points to a biological root cause for the seasonal variation in viral upper respiratory tract infections we see each year, most recently demonstrated throughout the COVID-19 pandemic.
Researchers say this finding could lead to better ways to boost the nose’s immune response during colder times of the year.
For example, a nasal spray could be used to increase the number of extracellular vesicles in the nose, or possibly to increase the number of binding receptors inside the vesicles.
For tips on staying healthy this winter, check out “3 flu shots recommended for seniors.”