Common cold prevents flu virus from developing, Yale study discovers

Could the discovery mean the rhinovirus will be a major factor in how the coronavirus spreads this fall and winter?

NEW HAVEN, Conn. — Can’t stand those nagging fall and wintertime colds? Well, here’s one good reason to appreciate them: it turns out that the common cold may protect against the flu virus. Researchers at Yale University say that’s because cold viruses yield a powerful immune system response that keeps an influenza infection from developing.

The findings now have researchers wondering if a similar result is possible in patients suffering from the coronavirus.

There’s certainly nothing fun about that nonstop runny nose or coughing fits associated with rhinovirus, the most frequent cause of the common cold. But doctors made an interesting discovery when looking at three years of data from more than 13,000 patients at Yale New Haven Hospital. They found when rhinovirus was present in a patient — particularly during cold and flu season — influenza was not.

“When we looked at the data, it became clear that very few people had both viruses at the same time,” says Dr. Ellen Foxman, assistant professor of laboratory medicine and immunobiology and senior author of the study, in a release.

How the common cold shields us from the flu virus

Foxman says rhinovirus “jumpstarts” production of interferon, an antiviral agent that occurs when viruses or bacteria enter the body. “The antiviral defenses were already turned on before the flu virus arrived,” she notes.

To be sure, researchers used stem cells to create human airway tissue that would typically become infected by a respiratory virus. Incredibly, they confirmed that when the tissue was already infected with rhinovirus, the flu virus couldn’t infect it at the same time.

“The effect lasted for at least five days,” says Foxman.

Could the coronavirus outbreak this winter be slowed?

The authors believe that the findings could explain why the 2009 H1N1 swine flu pandemic never took grip of Europe. That outbreak occurred in the fall, when the common cold typically begins its annual spread. Still, Foxman isn’t sure whether Americans could see a similar impact on the spread of the coronavirus later this year.

One recent study, however, does report that the common cold could protect against SARS-CoV-2, the virus that causes COVID-19. Foxman and her team are already investigating whether or not such an effect is indeed likely.

The findings are published in the journal The Lancet Microbe.

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