Widespread chilly combats influenza

Common cold combats influenza

A representation of the molecular surface of a variant of the human rhinovirus. Photo credit: Wikipedia / CC BY-SA 3.0

As the flu season approaches, a strained public health system may have a surprising ally – the cold virus.

The number one cause of colds, rhinovirus can prevent the flu virus from infecting the respiratory tract by boosting the body's antiviral defenses, Yale researchers reported in The Lancet Microbe on Sept. 4.

The results help solve a riddle surrounding the 2009 H1N1 swine flu pandemic: an expected surge in swine flu cases never occurred in Europe in autumn, a time when the common cold was spreading.

A Yale team led by Dr. For three years, Ellen Foxman studied clinical data from more than 13,000 patients examined at Yale New Haven Hospital with symptoms of a respiratory infection. The researchers found that even for months when both viruses were active, the flu virus was not present if the cold virus was present.

"When we looked at the data, it became clear that very few people had both viruses at the same time," said Foxman, assistant professor of laboratory medicine and immunobiology and lead author on the study.

Foxman stressed that scientists do not know whether the annual seasonal spread of the common cold virus will have a similar impact on the infection rates of those exposed to the coronavirus that causes COVID-19.

"It's impossible to predict how two viruses will interact without doing the research," she said.

To test how the rhinovirus and influenza virus interact, Foxman's lab made human airway tissue from stem cells that make epithelial cells that line the airways of the lungs and are a primary target of respiratory viruses. They found that the influenza virus could not infect the tissue after the tissue was exposed to the rhinovirus.

"The antiviral defense was activated even before the flu virus hit," she said.

The presence of rhinovirus triggered the production of the antiviral agent interferon, which is part of the immune system's early response to invasion by pathogens, Foxman said.

"The effects lasted for at least five days," she said.

Foxman said her lab has begun looking into whether introducing the common cold virus will provide similar protection from infection with the COVID-19 virus.

The body is fighting the cold virus and other threats and making a compromise, the study says

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Yale University

Common cold combats influenza (2020, September 4)
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