Vaccines rarely cause serious side effects, health officials say. When problems do arise, they most often occur in people with preexisting immune system disorders.
The report, issued Thursday by an independent panel of medical experts convened by the Institute of Medicine -- which provides independent, science-based analyses -- should be used to help administer claims through the Vaccine Injury Compensation Program. That program was established in 1986 to provide financial compensation to people who were harmed by eight recommended vaccines.
Vaccine safety is a highly charged issue. Fears that vaccines can cause various side effects have led to a decline in childhood immunization rates in recent years and a re-emergence of preventable infectious diseases such as pertussis and measles.
“The utility of this report is enormous,” said Dr. Ellen Wright Clayton, the committee chairwoman and director of the Center for Biomedical Ethics and Society at Vanderbilt University. “Claimants and the government and the vaccine court will now have available to them the best analysis that has ever been done about the potential adverse events caused by these vaccines.”
The committee reviewed more than 1,000 scientific articles to assess vaccine safety. The report, the first comprehensive review of the issue by the Institute of Medicine since 1994, supports several previous analyses that failed to find a link between the measles-mumps-rubella vaccine and autism.
Moreover, the panel said they could find no evidence showing the diphtheria-tetanus-acellular pertussis vaccine causes type 1 diabetes or that the flu shot worsens asthma or causes Bell’s palsy, a nerve disorder that causes temporary paralysis of the muscles in the face.
However, committee members said they found evidence that various vaccines can cause a range of side effects, usually minor, such as fainting or soreness at the injection site. For example the measles-mumps-rubella vaccine can cause fever-related seizures, although such seizures rarely cause any permanent disability.
Six vaccines, including MMR, influenza, varicella, hepatitis B, meningococcal and tetanus can cause an allergic reaction as well anaphylaxis, a sudden, life-threatening allergic reaction, according to the report. The varicella vaccine can cause rare cases of pneumonia, meningitis, shingles, chickenpox and other conditions in people with immune-system disorders as well as some people with healthy immune systems.
Doctors typically a case-by-case decision on which vaccines should be avoided in immune-compromised patients, said Dr. Douglas J. Barrett, a professor of pediatrics at the University of Florida and a committee member.
The report does not answer one of the most pressing questions regarding vaccine safety. Gardasil, a vaccine to protect against common strains of human papilloma virus that can cause cervical cancer, has been linked in isolated case reports to blood clots and even some deaths. But the report says there is not enough scientific evidence yet to determine whether HPV vaccines can cause side effects.
“We did not find studies that were sound enough to consider to making any kind of judgement on that association,” said Dr. S. Claiborne Johnston, a committee member and professor of neurology and epidemiology at UC, San Francisco.
But, Clayton said of the evidence on HPV vaccine: “There was nothing that was alarming, so far.
The report did not explore the benefits of population-wide vaccine programs versus the costs of adverse events in some individuals. Moreover, the committee did not review the scientific evidence on whether safety profiles of various vaccines change when they are given in combinations.
Vaccines are credited with dramatic plunge in several infections diseases over the last half century, such as polio, tuberculosis and rubella, Clayton said.
“We have a lot of evidence that vaccines save lives and avert a lot of suffering,” she said. “The side effects we’re talking about here are relatively rare. It’s hard to find them when you’re looking in a general population. And the majority of ones we found are short-term or readily treated.”
The report should help pediatricians and family practitioners allay parents’ concerns over vaccine safety, Johnston said. A report released last year by the nonprofit National Committee for Quality Assurance found vaccination rates among toddlers covered in private health insurance plans fell almost 4% in 2009.
“It actually is quite reassuring for somebody who is making a decision about getting a vaccine,” he said.
But a finer review of the lengthy report shows not enough scientific evidence exists to guarantee the safety of certain vaccines, said Barbara Loe Fisher, co-founder and president of the National Vaccine Information Center, a nonprofit organization in Vienna, Va.
“The most important finding is that in the majority of cases when they looked at the scientific literature, there was inadequate evidence for them to accept or reject causation” of adverse events, she said. “I think that points out the urgent need for more high-quality vaccine safety science.”
Fisher said she disagreed with some of the committee’s findings, such as the conclusion that vaccines cannot trigger Type 1 diabetes.
Many parents remained unconvinced that the MMR vaccine does not cause some cases of autism, she added. “I disagree that all the science has been done to put that effectively to rest.”
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