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Few risks are linked to vaccines, US committee finds

Adverse effects occur, but only in rare cases

By Deborah Kotz
Globe Staff / August 26, 2011

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The Institute of Medicine concluded yesterday in a comprehensive report on the safety of eight commonly used vaccines that “few health problems are caused by or clearly associated with vaccines.’’

In its review of more than 1,000 scientific studies, a committee of specialists, convened by the institute at the behest of Congress, found evidence of some adverse effects associated with vaccines - including seizures, inflammation of the brain, allergic reactions, and fainting - but said that these occurred only in rare cases.

They also said there was enough evidence to reject outright any links between immunizations and certain more serious health conditions including autism, type 1 diabetes, asthma, and Bell’s palsy.

“With the start of the school year, it’s time to ensure that children are up to date on their immunizations, making this report’s findings about the safety of these eight vaccines particularly timely,’’ committee chair Ellen Wright Clayton, director of the Center for Biomedical Ethics and Society at Vanderbilt University in Nashville, said in a statement. “The findings should be reassuring to parents that few health problems are clearly connected to immunization, and these effects occur relatively rarely.’’

The vaccines reviewed were measles-mumps-rubella, varicella (chickenpox), influenza, hepatitis A, hepatitis B, human papillomavirus (HPV), diptheria-tetanus-acellular pertussis, and meningococcal.

Of the 14 vaccine-associated side effects backed by solid evidence from studies, most were mild and temporary. The measles-mumps-rubella vaccine can cause febrile seizures in infants, which look scary to parents but vanish quickly and do not cause brain damage. It can also cause a rare form of brain inflammation in some people with severe immune system problems.

In a minority of patients, the chickenpox vaccine can cause infections with the varicella virus, leading to chickenpox or shingles, as well as pneumonia, hepatitis, and meningitis, the committee found, though most of these cases also occurred in people with immune system problems.

Six vaccines, including ones against chickenpox, flu, and tetanus, can cause anaphylaxis - a life-threatening whole-body allergic reaction - in those who are allergic. Some injections can cause fainting or temporary arm muscle inflammation.

For dozens of suspected vaccine-related injuries, the committee found there was not enough research to “accept or reject’’ a causal relationship. Some of these were based on case reports, like a teenage girl who developed paralysis after receiving her third injection of the HPV vaccine and later died. It turned out she had a genetic mutation that may have predisposed her to a juvenile form of Lou Gehrig’s disease.

The Institute of Medicine has reviewed the safety of vaccines 11 times at the request of Congress since it enacted the National Childhood Vaccine Injury Act in 1986, with the last review occurring in 1994. The Health and Human Services Department uses the reviews to administer the Vaccine Injury Compensation Program, which compensates the families of children injured by vaccines.

In recent years, the safety of vaccines has become the subject of intense debate. Some parents have raised concerns that the rising number of inoculations might be causing too many complications, leading some parents to refuse to get their children vaccinated.

Many public health authorities, however, have become increasingly alarmed that the refusals have led to a resurgence of diseases that can be life-threatening, such as measles. In fact, a large outbreak of measles occurred in Europe this year and the number of cases in the United States, including in Massachusetts, has been rising.

The report was praised by advocates for childhood vaccines. But critics noted that the committee acknowledged that there was insufficient evidence to reach conclusions about many concerns about vaccines.

“The committee’s clear acknowledgment that there is a lack of adequate scientific understanding about the way that vaccines act in the human body, including how, when, why, and for whom they are harmful, is confirmation that more and higher quality vaccine safety science is urgently needed,’’ Barbara Loe Fisher of the National Vaccine Information Center said.

Massachusetts has new vaccine requirements going into effect on Sept. 1: Students entering kindergarten, seventh grade, or college must have two doses of measles-mumps-rubella and two doses of varicella [chickenpox] vaccines. Seventh-graders and college freshmen also need a booster against tetanus, diptheria, and acellular pertussis, known as Tdap.

Material from the Washington Post was used in this report. Deborah Kotz can be reached at dkotz@globe.com.

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