- San Antonio - Faced with an ever-growing list of required
and recommended vaccinations for children -- as well as occasional reports
of safety problems linked to vaccines -- many parents understandably feel
confused. No doubt adding to that confusion are reports that the vaccine
against hepatitis B, a blood-borne illness that can cause liver cancer,
may actually lead to the development of type 1 diabetes in children.
- Type 1 diabetes is the form where the body doesn't make
the insulin it needs. An Italian study presented here at the annual meeting
of the American Diabetes Association suggests that children who get the
hepatitis B vaccine are at greater risk for developing type 1 disease than
those who have never been vaccinated. On the basis of their research, Paolo
Pozzilli, MD, and colleagues say doctors should exercise caution in giving
the vaccine to children who have close relatives with type 1 diabetes.
- But because type 1 diabetes is relatively rare in the
overall population, thorough studies involving several hundred thousand
participants are needed to prove a solid link, says Marion Rewers, MD,
who was not involved in the study. So the jury is still out, he says.
- "The possibility of a link between hepatitis B vaccine
[and type 1 diabetes] is an interesting research area and has been recognized
as such by a number of investigators across the world," he tells WebMD.
He says that at two recent meetings, researchers "were in unanimous
agreement that there was no association. We need a monitoring system, so
that if an association is found in the future, it can be promptly identified."
Rewers, a pediatric endocrinologist, is a professor of pediatrics and preventive
medicine at the University of Colorado in Denver and chair of the ADA council
on epidemiology and statistics.
- The CDC recommends that the hepatitis B vaccine be a
part of routine vaccination schedules for U.S. infants. The hepatitis B
vaccine is now required in Italy, says Pozzilli, a professor of pediatrics
at the University of Rome. Further, there is a low, relatively stable rate
of type 1 diabetes there. These conditions allowed the researchers to compare
the rate of diabetes in vaccinated children with that in unvaccinated groups.
- Investigators compared 150,000 children who had been
vaccinated at age 3 months to an equal number of unvaccinated children.
To assess the risk of developing type 1 diabetes in children who got the
vaccine later, after vaccination became mandatory in Italy, 400,000 children
who were vaccinated at age 12 were compared with children who had not been
- In the group as a whole, the rates of type 1 diabetes
were 46 per 100,000 for children who had been vaccinated and 34 per 100,000
for children who had not. For those vaccinated at age 12, the rates were
17.8 per 100,000 for vaccinated children and 6.9 per 100,000 for unvaccinated
- Although these may seem like large groups to study, they
are not big enough for scientists to see clear patterns for type 1 diabetes,
Rewers says. For a study like this to have value, the database should involve
as many as 250,000 people in both the vaccinated and unvaccinated groups,
he says. "Caution is necessary when the potential of vaccine-related
risks is studied," Rewers tells WebMD. "Without sound supportive
data, [parents] can become unduly alarmed and stop immunizing their children."
When immunization rates drop, diseases that can cause serious illness --
and death return, he tells WebMD.
- The National Institutes of Health and the CDC are jointly
establishing a system known as "sentinel monitoring areas," Rewers
tells WebMD. The agencies will track the rate of type 1 diabetes in these
areas -- consisting of selected counties in the U.S. -- and will determine
whether the rate is related to things like immunizations, recommended infant
feeding schedules, and outbreaks of infection.
- Rewers has not been involved with the development of
any vaccine and has no ties to any company that manufactures vaccines.
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