Scientists have discovered how we catch cold

The observation is the same every fall and every winter. when the thermostat drops, flu-like conditions rise again until spring: runny nose, scratchy throat, intense cough. We often say that we have a cold, but we don’t mean it. The new American study was published Tuesday, December 6 in the journal Journal of Allergy and Clinical Immunologyshows that cold air entering the body impairs the immune response, especially in the nose, making people catch colds more often.

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“Conventionally, cold and flu season occurs in the colder months because people are more often indoors, where airborne viruses can spread more easily. CNN: Benjamin Blair, MD, director of otolaryngology research at Mass Eye and Ear Hospital (Boston) and lead author of the study. These findings show that the cold actually halves our immune system’s ability to fight off respiratory infections.”

Weakened defense mechanism below minus 5°C

Along with the mouth, the nose is actually the main route of infection, as the germ is inhaled or deposited there by the hands. In 2018, American researchers had already discovered that there is an innate immune response that occurs when bacteria enter the nose. A kind of defense mechanism. Simply put, to defend against an invader, cells in the front of the nose detect signs of bacterial entry and respond by producing billions of tiny fluid-filled sacs called extracellular vesicles (or EVs). In addition, these EVs are fortified with protective proteins with antimicrobial properties.

“The best analogy is the hornet’s nest,” he explains AFP: Mansour Amiji, a professor at Northeastern University and co-author of this study. Like hornets defending a nest when attacked, VEs fly in swarms to join the invaders and kill them.”

The cold doubles our immune system’s ability to fight off respiratory infections

Dr. Benjamin Blair, lead author of the study

To support their investigations, the research team conducted additional tests in recent months to determine whether the EVs work in the presence of the virus and, if so, whether their response is affected by the outside temperature.

To do this, they took nasal mucosa from patients who had surgery to remove their polyps, or healthy volunteers, and exposed it to a substance that replicates a viral infection (two common rhinoviruses and a coronavirus, not Covid). The samples were divided into two groups and subjected to different temperatures.

Below 5°C, the researchers observed that the EVs’ immune defense system was less effective against common winter viruses. Their experiment shows that exposure to this level of temperature kills almost 50% of the billions of cells that fight viruses and bacteria in the nostrils, reports CNN: .

Not only do masks protect you from directly inhaling viruses, but they’re also like wearing a sweater over your nose.

Dr. Benjamin Blair, Director of Otolaryngology Research at Mass Eye and Ear

Towards a new treatment?

“There has never been a very convincing reason why there is an apparent increase in viral infectivity in the colder months. This is the first quantitative and biologically plausible explanation that has been developed, said Dr. Benjamin Blair in a press release.

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According to study co-author Mansour Amiji, this work could make it possible to develop a treatment that stimulates the natural production of VE, so that we can better fight colds or even flu and Covid-19. “This is a research field that interests us immensely, and we will undoubtedly continue on this path,” he assures.AFP:.

Waiting for more in-depth studies, one wonders how to protect oneself from the “cold”. With a mask, notes Dr. Benjamin Blair in the columns CNN: . Protects against inhalation of viruses… and warms.