The average American adult gets the common cold two to three times a year, and as winter approaches, the risk of getting sick rises.
For years, people have believed that the reason colder weather keeps people indoors is because it makes cold and flu viruses more prevalent. Additionally, diseases spread more quickly from one person to another when people are near to one another in a group.
However, recent research from a group at Massachusetts Eye and Ear Hospital and Northeastern University, released this month, reveals there may be biological reasons for why we are substantially more likely to become ill when temperatures drop.
How do viruses get into the nose?
Inhalation or direct contact with virus particles are the two ways that they can enter the nose.
Dr. Benjamin Bleier, director of Otolaryngology Translational Research at Massachusetts, said: “The nose is one of the first sites of contact between the outside world and within the body.” Co-author of the study that was included in The Journal of Allergy and Clinical Immunology, Eye and Ear
The cells in our nasal canals quickly activate to begin expelling virus particles when they enter. However, the results of the recent study show that this immunological response is greatly impaired by cooler temperatures.
Viruses and the nose: What happens
To better comprehend what transpires when a virus enters the nasal passage, let’s go back a few steps.
In 2018, Bleier and a group of Massachusetts-based scientists published their findings. Researchers from Eye & Ear and Northeastern University discovered that when germs are detected by nasal cells at the front of the nose, billions of small fluid-filled sacs are released.
Extracellular vesicles (EVs), as Bleier told Healthline, swiftly move into the mucus to “surround and attack the bacteria before they have a chance to infect the cells.”
In essence, these EVs try to eliminate the germs before they may start to seriously infect the body.
The next step was to encourage the researchers to look at what happens when viruses enter the nose.
This prompted Bleier’s team to investigate if typical upper respiratory diseases like the common cold are caused by viruses that exhibit a similar reaction.
They discovered that the EVs are released and react in the same way to all three types of common cold viruses, enveloping and killing any viral particles found in the mucus.
According to Bleier, “These vesicles carried chemicals (called microRNA), which subsequently destroyed the viruses.” The EVs were “essentially sweeping up the viruses before they could bind to the cells,” according to this.
However, the inquiries didn’t stop there. Bleier and his team proposed that the cold air might affect this nasal immune response because colds and flu are more prevalent in the winter.
So they heated nasal tissues to 39.9° F or 4.4° C, and discovered that doing so caused tissues to cool by roughly 9° F or 5° C, having a significant negative impact on the immune system.
According to Bleier, “This decline greatly lowered this innate immune response in the nose.”
Over 40% fewer EVs were released, and the quality of those that were still made was significantly worse.