With the cold of winter comes colds and flu, but why?
A new study published in the scientific journal The Journal of Allergy and Clinical Immunology points to an explanation for the increase in respiratory diseases when temperatures drop, attributing it to the fact that cold air damages the immune response in the nose.
Reducing the temperature in the nose by nine degrees Fahrenheit (five Celsius) kills almost half of the billions of cells in our body that fight viruses and bacteria.
"This is the first time that we have a biological explanation for a factor in our innate immune response, which seems to be limited by colder temperatures," Dr. Zara Patel, a professor of otolaryngology at Stanford University, told CNN news. , who did not participate in the study.
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When a microorganism enters through the nose, the cells that protect us create billions of copies called extracellular vesicles (EVs).
"They're like little miniature versions of cells designed specifically to go kill viruses," one of the study's authors, Benjamin Bleier, a professor at Harvard Medical School in Boston, told CNN.
“They act like decoys: when we inhale a virus, it sticks to these decoys instead of cells,” he explains.
Thus they are expelled by the cells into the nasal mucus, where invading germs are stopped before they can reach their destination and multiply.
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The study comes as respiratory syncytial virus (RSV) cases have peaked in some parts of the country, such as the South and Southeast, and leveled off on the East Coast and Midwest, he said Monday. the director of the Centers for Disease Control and Prevention (CDC), Rochelle Walensky.
Nationwide, the number of weekly positive RSV tests dropped from more than 19,000 in the week ending November 12 to about 7,500 in the week ending November 26.
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However, COVID-19 cases are up 16% since Thanksgiving week, and flu hospitalizations remain at a decade-high, Walensky added.
Approximately 78,000 people have been hospitalized for the flu since the beginning of October.
About 19,500 were admitted for the first time in the week ending Nov. 27, according to the Health Department, nearly double the number of flu hospitalizations recorded the previous week.
The CDC estimates that influenza has already caused 8.7 million infections since October 1.
A figure close to the 9 million estimated cases for the entire flu season from 2021 to 2022.
The CDC reported a nearly 18% increase in mean daily hospital admissions for COVID-19 between the week ending November 22 and the week ending November 29.
