Science has finally figured out why we are more likely to get ill in cold weather.
As it turns out, really low temperatures are able to lower immunity in the nose, making us much more vulnerable to all kinds of viruses entering the body.
Apparently, a slight drop in nasal tissue temperature of no more than 5 degrees Celsius will reduce one’s immune response by nearly half.
This is quite revolutionary given the fact that for years, it was believed that the reason we are more prone to contracting viruses in winter was that lower temperatures lead to spending more time indoors, and being in closer proximity to people.
Of course, this tends to cause the transmission of viral diseases more easily.
However, as mentioned before, one new study has revealed the real reason why we catch colds and the flu during the cold season.
The study, published in The Journal of Allergy and Clinical Immunology suggests that the reasons are biological rather than social.
The director of Otolaryngology Translational Research, Dr. Benjamin Bleier, explains that “The nose is one of the very first points of contact between the outside world and the inside of the body.”
Sure enough, as soon as virus particles enter the nose, the nasal cavities activate and begin to expel them but according to the study, this immune response is negatively affected by low temperatures.
To understand more about why this happens, we should know that we have nasal cells at the very front of the nose that can detect bacteria and activate the release of billions of microscopic fluid filled sacs known as extracellular vesicles or EVs.
Bleier previously shared via Healthline that EVs are quick to move into the mucus in order to “surround and attack bacteria before they have the chance to infect the cells.”
This was the conclusion of an older, 2018 study and the same team was encouraged to investigate further to figure out the consequences of the viruses entering the nose.
“This led our team to look at whether this response happened for some viruses that cause respiratory infections, such as the common cold,” Bleier dished.
The team also noticed that the EVs have the capacity to act like “decoys” as well, fooling the virus particles into attacking the EVs and not the actual nasal cells.
But to find out why this useful defense mechanism is so greatly impaired during cold weather, they exposed nasal tissues to temperatures of 4.4 degrees Celsius.
They noticed how this exposure caused a decrease in tissue temperature by 5 degrees Celsius and the unfortunate consequences that followed.
As it turns out, the number of EVs released decreased by more than 40 percent and their quality was also significantly compromised.
Bleier revealed that “This reduced reaction can make the virus more able to stick to and also infect the nasal cells. [This way] they can divide and cause infection.”
About the study, he also stated that as far as they are aware, it is “the first to offer a biological response to why people are more likely to develop respiratory infections like the cold, flu, and COVID-19 in colder temperatures.”