NEPA Vital Signs - Winter Spring 2018 - 10

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THE FLU
How the Vaccine is Developed &
Why It's Sometimes Not Effective

VER THE YEARS, THERE HAVE BEEN NUMEROUS
BREAKTHROUGHS IN THE MEDICAL FIELD THAT HAVE
SIGNIFICANTLY IMPACTED THE WORLD'S HEALTH.
wreak havoc that season. There are three main types of flu viruses
that affect humans including influenza A, influenza B, and influenza C, with the influenza A virus being the most common virus to
cause illness. Each of the types of influenza viruses have different
subtypes and each subtype has multiple variants due to mutations.
This leads to numerous different strains of the flu. Unfortunately,
the flu vaccine is only able to protect against the three or four
influenza viruses that research indicates are most likely to spread
and cause illness during the upcoming flu season. Each year the
vaccine composition is reviewed and updated as needed based on
which influenza viruses are making people sick, the extent to which
those viruses are spreading, and how well the previous season's
vaccine protected against those viruses. More than 100 national

The introduction of the first vaccine in 1794 was one of those
breakthroughs that has changed the world for the better. Vaccines
have wiped out smallpox and nearly eradicated polio. They are
able to control measles and mumps and protect travelers from
yellow fever. Most of these vaccines are so good that they require
only a few doses to cover a person for decades, or even for their
life. However, there is one vaccine that requires yearly dosing
and is not guaranteed to fully prevent infection. That vaccine
is the flu shot.
Each year before the start of the flu season, a new flu vaccine is
developed to try to fight the strains of the virus that are expected to

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NEPA Vital Signs - Winter Spring 2018

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