|NIAID Study Finds Higher Dose of Flu Vaccine Improves Immune
Response in the Elderly
There may be a simple way to provide elderly Americans with extra protection
against the annual flu virus: give them a higher dose of seasonal flu vaccine.
This idea is suggested by the results of a newly reported clinical trial supported
by the National Institute of Allergy and Infectious Diseases (NIAID), a component
of the National Institutes of Health (NIH).
The trial, described in the latest issue of the Archives of Internal Medicine,
was conducted by a team of researchers from Baylor College of Medicine in Houston,
TX, and sanofi pasteur, the vaccines business of the sanofi-aventis Group in
Paris. Led by Dr. Wendy Keitel, M.D., the team conducted the trial at the Baylor
Vaccine and Treatment Evaluation Unit, which is one of a network of NIAID-supported
sites at university research hospitals across the United States that conduct
Phase I and II clinical trials to test and evaluate candidate vaccines for infectious
NIH Director Elias A. Zerhouni, M.D., notes, “The study results reported by
Dr. Keitel and her colleagues are important because they suggest that a higher
dose of seasonal influenza vaccine can safely and significantly increase the
immune responses of older people.”
“Elderly Americans are among the most vulnerable to serious complications of
influenza because they generally have more underlying diseases and weaker immune
systems than younger people,” says NIAID Director Anthony S. Fauci, M.D. “These
findings are an important first step in developing new strategies to better protect
the elderly against influenza-associated hospitalizations and mortality.”
“If you look at people who are dying and going into the hospital during an outbreak
of seasonal influenza,” says Dr. Keitel, “the majority of those people are older
Influenza accounts for some 36,000 deaths and more than 200,000 hospitalizations
every year in the United States. It is among America’s most lethal killers simply
because the virus infects so many people — some 5 to 20 percent of the
U.S. population every year.
In other influenza vaccine studies, higher antibody levels resulted in better
protection against infection. Conversely, decreased antibody production in the
elderly can leave them more susceptible to infection and the severe complications
of influenza. Helping elderly people increase antibody production should help
them fight off influenza infections, and this is exactly what Dr. Keitel and
her colleagues set out to test when they began the clinical trial. They hypothesized
that elderly people could be given higher doses of vaccine safely and that these
higher doses would increase the antibody response and confer increased protection
without increasing side effects.
In the study, the investigators randomly assigned 202 adults 65 years of age
or older into four 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
years. All study participants were followed for a month post-vaccination to look
for any vaccine-related side effects and to collect blood to evaluate antibody
Dr. Keitel and her colleagues found that participants in the high-dose group
(60 micrograms) had 44 to 79 percent higher levels of antibody than did those
who received the normal dose of vaccine. Higher doses also increased the number
of elderly volunteers achieving levels of antibody that have been associated
with protection against influenza. Moreover, the vaccine was well-tolerated at
all dosage levels. Although the higher doses of vaccine caused more mild side
effects at the injection site, there were no significant differences in systemic
symptoms such as fever or body aches among the groups.
The successful achievement of higher levels of antibodies in this study suggests
that larger doses of vaccine may be a safe and viable way of enhancing protection
against influenza among elderly persons. These promising results provide a basis
for further evaluation of enhanced potency vaccines in the elderly, says Dr.
For more information on influenza see http://www3.niaid.nih.gov/news/focuson/flu.
Also visit http://www.PandemicFlu.gov for
one-stop access to U.S. Government information on avian and pandemic flu.
NIAID is a component of the National Institutes of Health, an agency of
the U.S. Department of Health and Human Services. NIAID supports basic and
applied research to prevent, diagnose and treat infectious diseases such as
HIV/AIDS and other sexually transmitted infections, influenza, tuberculosis,
malaria and illness from potential agents of bioterrorism. NIAID also supports
research on transplantation and immune-related illnesses, including autoimmune
disorders, asthma and allergies.
The National Institutes of Health (NIH) — The Nation's Medical Research
Agency — includes 27 Institutes and Centers and is a component of
the U.S. Department of Health and Human Services. It is the primary federal
agency for conducting and supporting basic, clinical and translational medical
research, and it investigates the causes, treatments, and cures for both common
and rare diseases. For more information about NIH and its programs, visit www.nih.gov.