Colds and winter viruses: scientists explain how we catch colds

The cold is a factor in the circulation of viruses. (© illustrissima / Adobe Stock)

“Put on your scarf, you’re catching a cold!” ”: how many children have already heard this remark from their parents? Unquantifiable.

But with the resurgence of Covid, flu or even bronchiolitis, winter illnesses, the relationship between colds and viruses intrigues a little more. Why the hell do we get sicker in the winter?

A study, published Tuesday, December 6, 2022 in Journal of Allergy and Clinical Immunologyputs a new hypothesis on the table to explain that we can “catch a cold”.

What the survey tells us

First of all, it must be understood that there is one defense mechanism present in our nostrils. When a bacterium is inhaled, the nasal cells release extracellular vesicles which attack them.

With this new study, the researchers tried to find out whether the reaction of the extracellular vesicles was the same with winter virus. So they tested two rhinoviruses and one coronavirus [ce n’est pas le Covid-19, N.D.L.R]once with normal temperatures and once with cool temperatures.

At normal temperatures, extracellular vesicles fight viruses well by presenting “decoys” to which viruses can bind. An antiviral function that helps defend the body.

On the other hand, when it is cold, the study highlights “a modification” of this defense mechanism antiviral. So logically, we are more susceptible to viruses in winter when it is colder.

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A factor…

But this study does not contradict previous claims that already indicated that the cold increases the risk of getting sick. She comes Besides.

“It’s always the problem with the cold and the respiratory mucous membranes”, notes Henri Agut, former head of the virology department at the Pitié-Salpêtrière hospital in Paris, contacted by news.fr.

The respiratory mucosa works worse in winter. The explanation for extracellular vesicles is one of many factors, but is not the only one.

Henrik AgutFormer head of the virology department at the Pitié-Salpêtrière hospital

And we can see it right now, covid, flu and bronchiolitis are enjoying these cool winter temperatures too circulate actively in the population. “Some viruses infect more easily in winter because the defense mechanisms have changed”, explains the one who is also the founder of the review. Virology.

… among other

It is well understood that the extracellular vesicles and their alteration in the cold are not the only ones responsible for a decrease in antiviral defense in winter. Others must be considered.

” That immune system and respiratory system does not like the cold. They work worse at low temperatures,” recalls Henri Agut. While viruses survive better at low temperatures.

François Bricaire, an infectious disease physician, made another observation in an earlier article: “The common cold mobilizes the individual’s energy, as the body tries to defend itself. We are therefore less strong to fight the cold, and by extension more sensitive to viral infections”.

More inside

Finally promiscuity is also a phenomenon to take into account when arriving in winter. If in the summer we tend to meet outside, on the terrace or around a barbecue, in the winter we are more often indoors because of the coolness.

People regroup. This is probably what puts you at a greater risk of infection.

Francois Bricairespecialist in infectious diseases

And faced with these viral threats and the episode of freshness in France, the government and doctors agree on a response to give: respect barrier movements.

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