The Toddler Vaccine Debate
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www.washingtonpost.com/wp-dyn/content/article/2006/01/30/AR2006013001253_pf.html
The Washington Post
The Toddler Debate
Tuesday, January 31, 2006; HE02
U.S. infectious disease experts last week dismissed suggestions that there
is insufficient evidence for recommending routine flu shots for healthy
children between 6 and 23 months of age.
A review published by the Cochrane Collaboration, an international
organization that evaluates medical research, looked at 51 studies worldwide
involving more than 250,000 children under age 16. The review uncovered few
studies of children under age 2, and found that in studies of vaccines using
killed virus -- the only kind approved for use in children under 5 -- shots
were no more effective than placebo.
The report didn't carry much weight with U.S. health experts.
John Bradley, director of infectious disease at Children's Hospital in San
Diego and a member of the American Academy of Pediatrics committee on
infectious diseases, termed the Cochrane review exhaustive and meticulous --
but unpersuasive.
Missing Data In gathering published research dating back to 1976, Bradley
said, the reviewers failed to account for variation in the quality of
vaccines and research methods. The review, he said, also fails to account
for the fact that much of the efficacy data on vaccines is gathered by drug
companies that may choose for business reasons not to publish their
findings.
"The data that [the researchers] have collected doesn't prove that
vaccination doesn't work," Bradley said.
U.S. flu experts agree more research is needed but say there is no reason to
question the vaccine's safety for toddlers. Ray Strikas, a flu specialist at
the Centers for Disease Control and Prevention (CDC), said the agency's
decision to add toddlers to the priority groups for flu vaccine in 2004 was
based on U.S. studies showing high rates of serious flu complications in
children under 2.
"It was driven by fairly high rates of hospitalization and illness in these
kids, with the knowledge that there are not a lot of data about . . .
vaccine effectiveness in this population," Strikas said. "We felt there was
enough data to say that the vaccine does work -- kids do make [flu]
antibodies -- and that it was a reasonable thing to recommend because it's a
safe vaccine and all the data suggest it should be effective."
Get the Shot The CDC and the American Academy of Pediatrics continue to
recommend annual flu shots for children under 2. They're considering
extending the recommendation to include all children up to age 6.
-- Gregory Mott
Cochrane Database Syst Rev. 2006 Jan 25;(1):CD004879. Links
ABSTRACT
Vaccines for preventing influenza in healthy children.
Smith S, Demicheli V, Di Pietrantonj C, Harnden A, Jefferson T, Matheson Nj,
Rivetti A.
BACKGROUND: In children and adults the consequences of influenza are mainly
absences from school and work, however the risk of complications is greatest
in children and people over 65 years old. OBJECTIVES: To appraise all
comparative studies evaluating the effects of influenza vaccines in healthy
children; assess vaccine efficacy (prevention of confirmed influenza) and
effectiveness (prevention of influenza-like illness) and document adverse
events associated with receiving influenza vaccines.
SEARCH STRATEGY: We
searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The
Cochrane Library Issue 1, 2005); OLD MEDLINE (1966 to 1969); MEDLINE (1969
to December 2004); EMBASE (1974 to December 2004); Biological Abstracts
(1969 to December 2004); and Science Citation Index (1974 to December 2004).
We wrote to vaccine manufacturers and a number of corresponding authors of
studies in the review.
SELECTION CRITERIA: Any randomised controlled trials
(RCTs), cohort and case-control studies of any influenza vaccine in healthy
children under 16 years old.
DATA COLLECTION AND ANALYSIS: Two authors
independently assessed trial quality and extracted data. MAIN RESULTS:
Fifty-one studies involving 263,987 children were included. Seventeen papers
were translated from Russian. Fourteen RCTs and 11 cohort studies were
included in the analysis of vaccine efficacy and effectiveness. From RCTs,
live vaccines showed an efficacy of 79% (95% confidence interval (CI) 48% to
92%) and an effectiveness of 33% (95% CI 28% to 38%) in children older than
two years compared with placebo or no intervention.
Inactivated vaccines had
a lower efficacy of 59% (95% CI 41% to 71%) than live vaccines but similar
effectiveness: 36% (95% CI 24% to 46%). In children under two, the efficacy
of inactivated vaccine was similar to placebo. Thirty-four reports
containing safety outcomes were included, 22 including live vaccines, 8
inactivated vaccines and 4 both types.
The most commonly presented
short-term outcomes were temperature and local reactions. The variability in
design of studies and presentation of data was such that meta-analysis of
safety outcome data was not feasible.
AUTHORS' CONCLUSIONS: Influenza
vaccines are efficacious in children older than two years but little
evidence is available for children under two. There was a marked difference
between vaccine efficacy and effectiveness. That no safety comparisons could
be carried out emphasizes the need for standardisation of methods and
presentation of vaccine safety data in future studies. It was surprising to
find only one study of inactivated vaccine in children under two years,
given recent recommendations to vaccinate healthy children from six months
old in the USA and Canada.
If immunisation in children is to be recommended
as public-health policy, large-scale studies assessing important outcomes
and directly comparing vaccine types are urgently required
