Recent studies show
that flu vaccination reduces the risk of flu illness by between 40% and
60% among the overall population during seasons when most circulating flu
viruses are well-matched to the flu vaccine.
In general, current flu vaccines
tend to work better against influenza B and influenza A(H1N1) viruses and offer
lower protection against influenza A(H3N2) viruses.
Seasonal flu vaccines
are designed to protect against infection and illness caused by the three or
four influenza viruses (depending on vaccine) that research indicates will be
most common during the flu season. “Trivalent” flu vaccines are formulated to
protect against three flu viruses, and “quadrivalent” flu vaccines protect against
four flu viruses.
Flu vaccines do NOT protect against infection and illness
caused by other viruses that also can cause flu-like symptoms.
Vaccination against
influenza began in the 1930s with large scale availability in the United States
beginning in 1945. It is on the World Health Organization's List of
Essential Medicines, the most effective and safe medicines needed in a health
system.
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