Flu
vaccines provide virtually no benefit to children. That's
the conclusion of a new review of all relevant studies.
Interestingly, the news comes at a time when some health
officials have begun to recommend the vaccination of all
children in order to prevent them from passing on the
flu to their elderly relatives. The review follows on
the heels of a study that looked at three decades' worth
of data and found that vaccines for the elderly are not
as effective as previously thought. And contrary to conventional
medical wisdom, vaccines do not seem to reduce flu-related
deaths in elderly people.
To
determine the value of flu vaccines to children, Tom Jefferson,
MD, and colleagues at the Cochrane Collaboration looked
at over a thousand studies. They selected 14 high-quality
clinical trials in which vaccinated children had been
compared with unvaccinated children. The combined results
of these 14 trials were reported in the British journal
The Lancet (2/26/05). Here's the conclusion: “We recorded
no convincing evidence that vaccines can reduce mortality,
[hospital] admissions, serious complications, and community
transmission of influenza.”
The
best the Cochrane reviewers could come up was this: “Vaccines
were somewhat effective at reducing school absence…” Though
the U.S. Centers for Disease Control (CDC) and Prevention
advises flu vaccines for babies 6-23 months because they
tend to suffer more complications once they get the flu,
no evidence supports the recommendation. The Cochrane
reviewers found that vaccines had little effect on bronchitis,
ear infections, and hospitalizations, compared with the
babies given placebo vaccines. In short, the CDC recommendations
are irresponsible given the fact that the only two studies
that involved babies found no benefit and little is known
about adverse effects of these vaccines for babies.
Benefit
to Elderly overrated
Now
for the importance of flu vaccines to the elderly. A new
comprehensive study cast doubt on the widespread belief
that flu vaccines save lives (Archives of Internal Medicine,
2/14/05). Though the authors work for a federal government
health agency, they produced evidence that failed to support
CDC recommendations.
Lone
Simonsen, PhD, and colleagues at the National Institute
of Allergy and Infectious Diseases conducted a review
of 33 consecutive flu seasons, from 1968 to 2001. The
authors began their report with an acknowledgement that
an accurate assessment of flu-related deaths is virtually
impossible because few cases are confirmed with blood
tests. And the viral infection is usually cleared from
the body before the appearance of complications that cause
death. For these reasons, the authors had to use a special
statistical method to estimate flu-related deaths and
deaths from all causes among elderly Americans over the
three-decade-period.
Here
is what Dr. Simonsen and colleagues found:
-The
number of flu-related deaths among elderly Americans increased
steadily during the 33-year-period, despite the fact that
their acceptance of flu vaccinations also steadily increased.
For example, only 20% of all elderly Americans had a flu
shot in 1980, compared with 65% in 2001.
-There
was a decline in flu-related deaths among people 65-74
years in the decade after the 1968 flu pandemic because
people had naturally acquired immunity due to exposure
to the emerging viruses of that period. The increasing
flu vaccine coverage after 1980, however, did not correlate
with a decline in flu-related deaths.
-The
over-all death rate for people over 85 during flu seasons
did not change over the 33-year-period. Dr. Simonsen and
colleagues cite earlier research that might provide an
explanation for why flu vaccines did not reduce the flu-related
deaths in “the very elderly” after 1980 when vaccine coverage
began to increase, “...antibody responses following influenza
vaccination decline sharply after age 65 years and a clinical
trial involving subjects 60 years or older...found that
the efficacy of influenza vaccine in preventing influenza
illness was lower in people older than 70 years.”
Because
fewer than 10% of all winter deaths can be attributed
to the flu in any year during this study's three-decade
period, the authors conclude that vaccination's benefit
to elderly people has been substantially overestimated.
Maryann
Napoli, Center for Medical Consumers (C) March 2005.
