Scientists make breakthrough discovery: Why people get more colds in winter

This research is right on the nose.

Scientists have discovered why people get more colds during the winter months in research the medical community is hailing as a breakthrough.

A study published Tuesday in the Journal of Allergy and Clinical Immunology found that cold air weakens the body’s immune response — especially in the nose, which is one of the first sites of contact for respiratory viruses and an important part of the body’s immune response.

The research found that reducing the temperature inside the nose by just 9 degrees Fahrenheit kills nearly 50% of the billions of virus and bacteria-fighting cells in the nostrils.

“Cold air is associated with increased viral infection because you’ve essentially lost half of your immunity just by that small drop in temperature,” said rhinologist Dr. Benjamin Bleier, director of otolaryngology at Massachusetts Eye and Ear and an associate professor at Harvard Medical School in Boston, who co-authored the study.

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The findings account for why the colder months of the year are referred to as flu season since the cold wintry air can freeze out half of your body’s natural line of immunity.

“This is the first time that we have a biologic, molecular explanation regarding one factor of our innate immune response that appears to be limited by colder temperatures,” rhinologist and Stanford University School of Medicine professor Dr. Zara Patel, who was not involved in the study, told CNN.

Bleier and his team exposed four participants to 15 minutes of 40-degree Fahrenheit temperatures and then measured the state inside their noses for the study, which was completed in vitro — using human tissue in the lab rather than being tested on a living subject.

Research shows that when a virus or bacteria enters the nose, it is quickly detected in the front before reaching the back and signals for the cells lining the nose to begin replicating into decoy extracellular vesicles.

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“[Extracellular vesicles] can’t divide like cells can, but they are like little mini versions of cells specifically designed to go and kill these viruses,” Bleier explained to CNN. “EVs act as decoys, so now when you inhale a virus, the virus sticks to these decoys instead of sticking to the cells.”

The EVs are then expelled into mucus, as the body fights to stop the invading germs before they enter the body further and multiply. When invaded by germs, the nose increases the production of EVs by 160%, the study found.

“This is one of, if not the only part of the immune system that leaves your body to go fight the bacteria and viruses before they actually get into your body,” Bleier stated. “The body mops up these inhaled viruses, so they can never get into the cell in the first place.”

EVs have up to 20 times more receptors than original cells that enhance their ability to catch the unwanted germs, acting like little arms reaching out and grabbing the harmful particles as they are inhaled, study authors explained.

But Bleier and his team discovered that being exposed to cold air will “essentially knock out” the immunity advantages that the body naturally creates in a warm environment.

Just a few degrees drop in temperature was enough to remove nearly 42% of EVs, according to researchers, and those that do remain were found to have 70% fewer receptors.

The reduction in EVs and changes to those that are produced cut the immune system’s ability to fight off respiratory infections by half, the findings showed.

To help the production of plentiful and effective EVs, experts are yet again advising people to wear masks.

“Not only do masks protect you from the direct inhalation of viruses,” Bleier explained, “but it’s also like wearing a sweater on your nose.”