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Flu Shot
EXAMINING
PERFORMANCE
Flu shots have been a key component of illness prevention for
decades. Recent research examines how effective flu shots
have been over time for different segments of the population.
FLU SHOTS, ORIGINALLY developed during World War II
by Jonas Salk and Thomas Francis, are associated with
saving lives. In fact, the US Centers for Disease Control
and Prevention (CDC) recommends the annual
immunization for everyone older than six months.
However, until 2011, no single study had taken
into account all of the available literature about the
performance of influenza vaccines, writes Michael
Osterholm and his fellow researchers from the Center
for Infection Disease Research and Policy (CIDRAP) at
the University of Minnesota. Published in 2012 in The
Lancet, research performed by Osterholm's team covers
5,707 articles and 31 studies. The CIDRAP study differs
from others because it amasses and compares research on
real-world flu prevention associated with flu vaccinations,
rather than focusing on serology, or vaccinated people's
blood work. Essentially, the study found:
• Influenza vaccination is moderately effective against
the flu.
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• The vaccine is more effective in certain groups than
others and does not protect all the people all the time.
• Different kinds of flu vaccines have different
efficacy levels.
What Works When
The Minnesota researchers noted that 67 percent
of studies found that the trivalent inactivated influenza
vaccine, or TIV, was effective during the influenza
seasons covered. Seventy-five percent of the studies of live
attenuated influenza vaccine, or LAIV, showed "significant
efficacy," and the rest showed lower efficacies.
Differences in age explain part of the variation,
according to the Osterholm study. LAIV provides a
"consistently higher level of protection in children …
seven years and younger." Only one study featuring
LAIV showed "significant efficacy" for the 65 and
older age group.
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