Vaccines rarely cause any health problems and do not cause serious conditions such as diabetes or autism, an Institute of Medicine panel said on Thursday.
The panel of experts reviewed more than 1,000 studies and found that certain vaccines can cause rare and transient effects including seizures, inflammation of the brain, and fainting.
"The findings should be reassuring to parents that few health problems are clearly connected to immunizations, and these effects occur relatively rarely,” Ellen Wright Clayton, professor of pediatrics and law at Vanderbilt University in Nashville, Tenn., said in a statement.
“And repeated study has made clear that some health problems are not caused by vaccines."
The review is meant to help the Health and Human Services Department administer the Vaccine Injury Compensation Program – a fund to help pay the medical costs of people who are hurt by vaccines. The program, paid for by a tax on vaccines, is a no-fault system that automatically pays if a patient develops a condition that experts agree was likely caused by a vaccine.
The review showed there is convincing evidence that the measles-mumps-rubella or MMR vaccine can cause fever-triggered seizures in some people, although they almost never have lasting effects.
MMR vaccines also can cause a rare form of brain inflammation in some people with severe immune-system deficiencies.
In addition, the chickenpox vaccine can cause brain swelling, pneumonia, hepatitis and other effects in some people with immune deficiencies and in a few apparently healthy people, said the panel of the institute, an independent body that advises the federal government on medical matters.
But the MMR vaccine and diphtheria-tetanus-acellular pertussis DTaP vaccine do not cause Type 1 diabetes or autism, nor does the flu shot cause Bell's palsy or worsen asthma, the study found.
There is a significant minority of parents who believe these are real risks and who have refused to vaccinate their children – something health experts say puts not only these children at risk, but those around them.
Separately, the U.S. Centers for Disease Control and Prevention reported that only 49 percent of U.S. girls who are advised to get a vaccine to prevent cancer have received one.
The HPV vaccine protects against a wart virus called human papillomavirus, which causes virtually all cases of cervical cancer, as well as anal, penile and oral cancers. Girls aged 11 or 12 are supposed to start getting the first of the three-shot series of HPV vaccines.
The CDC said only 32 percent of girls who were supposed to get all three shots had gotten them.
"Our progress is stagnating, and if we don’t make major changes, far too many girls in this generation will remain vulnerable to cervical cancer later in life. Now that we have the tools to prevent most cervical cancers, it is critical
that we use them," Dr. Anne Schuchat, director of CDC's immunization programs, said in a statement.