Scientists discover the key reason the flu is so potent in winter

Yale researchers have discovered the flu virus’s best friend.

The flu virus’s best friend

Yale researchers have pinpointed a key reason why people are more likely to get sick and even die from the flu during winter months: low humidity.

While experts know that cold temperatures and low humidity promote transmission of the flu virus, less is understood about the effect of decreased humidity on the immune system’s defences against flu infection.

The Yale research team, led by Professor Akiko Iwasaki, explored the question using mice genetically modified to resist viral infection as humans do.

The mice were all housed in chambers at the same temperature, but with either low or normal humidity. They were then exposed to the influenza A virus.

The researchers found that low humidity hindered the immune response of the animals in three ways.

It prevented cilia, which are hair-like structures in airway cells, from removing viral particles and mucus.

It also reduced the ability of airway cells to repair damage caused by the virus in the lungs.

The third mechanism involved interferons, or signalling proteins released by virus-infected cells, to alert neighbouring cells to the viral threat. In the low-humidity environment, this innate immune defence system failed.

The study offers significant insight into why the flu is more prevalent when the air is dry.

“It’s well known that where humidity drops, a spike in flu incidence and mortality occurs. If our findings in mice hold up in humans, our study provides a possible mechanism underlying this seasonal nature of flu disease,” said Prof. Iwasaki.

While the researchers emphasised that humidity is not the only factor in flu outbreaks, it is an important one that should be considered during the winter season.

Increasing water vapor in the air with humidifiers at home, school, work and even hospital environments is a potential strategy to reduce flu symptoms and speed recovery, they said.

Do you use a humidifier at home? Have you found yourself more resistant to the flu than other people you socialise with? Do you think this could be the reason?

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    Health disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.


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    26th Jun 2019
    Low humidity has always existed in Victoria and the flu was never a problem. Our airports were not open 24/7 back then unlike now. They are full of people coming and going from developing countries with exotic flu.

    I think flu outbreaks are due to overcrowded, congested public transport full of sick people spluttering and spreading their bacteria to all.

    So many people with the flue in casual work dealing with the public spread their bacteria to work colleagues and customers too. Yesterday at Officeworks all the serving staff were coughing and spluttering all over the place. Casual work should include holiday and sick pay so that workers can afford to take a day off when they are sick.
    26th Jun 2019
    does this mean I should leave the exhaust fan off when I have a shower
    26th Jun 2019
    does this mean I should leave the exhaust fan off when I have a shower
    26th Jun 2019
    I would have thought that the opposite is more true.
    That the virus survives better in the natural environment when the air is moist (high humidity) Much like the way legionella bacteria survive in the misty vapor from aircon cooling towers?

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