Higher Dose of Seasonal Flu Vaccine Provides Extra Protection
A
new clinical trial suggests there may be a simple way to provide elderly Americans
with extra protection against the seasonal flu: give them a higher dose of vaccine.
Seasonal influenza, or seasonal flu, accounts for some 36,000 deaths and more
than 200,000 hospitalizations every year in the United States. It's among America's
most lethal killers because the virus infects so many people — 5 to 20%
of the population every year.
Previous seasonal influenza vaccine studies have found that the higher the levels
of the virus-fighting molecules called antibodies a person produces, the better
they're protected against infection. A team of researchers from the Baylor College
of Medicine and sanofi pasteur, the vaccines business of the sanofi-aventis Group,
set out to test whether elderly people could be given higher doses of vaccine
safely and whether the higher doses would increase their levels of antibody.
The trial, which was supported by NIH's National Institute of Allergy and Infectious
Diseases, is described in the latest issue of the Archives
of Internal Medicine.
The investigators randomly put 202 adults 65 years of age or older into 4 equal-sized
groups: those receiving the normal dose of vaccine (15 micrograms); twice the
normal dose (30 micrograms); four times the normal dose (60 micrograms); or a
placebo. The average age of the volunteers was 72.4. All were followed for a
month after vaccination to spot any vaccine-related side effects and to collect
blood to evaluate how much antibody their bodies made.
The researchers found that participants in the highest-dose group had 44 to
79% higher levels of antibody than those who received the normal vaccine dose.
The vaccine was well-tolerated at all dosage levels. While the higher doses of
vaccine caused more mild side effects at the injection site, there weren't significant
differences in symptoms such as fever or body aches.
Elderly Americans are among the most vulnerable to the serious complications
of seasonal influenza because they tend to have more underlying diseases and
weaker immune systems than younger people. This study suggests that giving the
elderly a higher dose of vaccine may be a safe way to help better protect them
from deadly bouts with the flu.
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