Articles, Blog

Why Is The Flu More Serious In The Winter?

November 21, 2019


Akiko Iwasaki, Immunologist>>It’s been known for many years in the winter months, that low temperature and low humidity is associated with flu mortality in humans. However it wasn’t really known
what causes this mortality in the winter months. What we found first of all
is that the low humidity impairs the ability of the
respiratory tract or the lung and the nose,
to get rid of the virus. In the airway cells there
are these cilia which are hair-like projections
that are constantly moving particles along to get rid
of these Inhaled particles. However in low humidity
what we found is that this cilia movement
as well as the particle removal was impaired. And this is particularly
important for people who are very susceptible such
as the very young infant or the older people above
age 65. The mortality from flu mostly
occurs in this age group. To increase humidity, there are a few things that one
might do, purchasing a humidifier
and humidifying your house or a workplace or hospital, is a direct way of increasing
humidity. [shower running sound] Take long hot showers and inhale very,very moist air and that seems
to also have some impact. Another reason we found
that humidity impacts the host disease in response
to flu, is that there is an impairment of innate
immune defense mechanisms that’s conferred by Type 1
interferons which are cytokines that are antiviral. These type 1 interferons
are important to induce hundreds of genes that counter
these viruses. However we found that the
low humidity impairs the expression
of these interferon and interferon stimulated genes. So how that happens at low
humidity is completely unknown. That’s another area for us
to study in the future. How does inhalation of low
humidity air impact immune defense against the virus? That’s a key new area of study.

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