Vaccines are associated with few health problems, a major review of studies on the topic by the Institute of Medicine confirms.
Released in August, the report shows that vaccines are not free from side effects, but those that do occur are rare or mild. Moreover, some health problems that develop following a vaccination are due to coincidence and are not caused by the vaccine, according to the report. Commissioned by the U.S. Department of Health and Human Services, the report aims to clarify the risks of eight vaccines covered by the federal Vaccine Injury Compensation Program to streamline compensation decisions.
“With the start of the new 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,” said Ellen Wright Clayton, MD, JD, chair of the report’s authoring committee and director of the Center for Biomedical Ethics and Society at Vanderbilt University.
In creating the report, researchers analyzed more than 1,000 scientific studies on the possible adverse effects of eight vaccines: hepatitis A; hepatitis B; human papillomavirus; influenza; measles, mumps and rubella; meningococcal; tetanus; and varicella zoster. According to the report, 14 health outcomes — including seizures, inflammation of the brain, allergic reactions, temporary joint pain and fainting — can be caused by certain vaccines, but such outcomes are rare. Moreover, researchers found no links between immunization and some serious conditions that have raised concerns, including Type 1 diabetes and autism.
According to the report, the majority of vaccine-related health problems occur in people with compromised immune systems. For example, the measles, mumps and rubella, or MMR, vaccine can possibly lead to fever-triggered seizures in some people, although the effects are almost always without long-term consequences. The MMR vaccine also can produce a rare form of brain inflammation in some people with severe immune system deficiencies. Also, the varicella vaccine, which protects against chickenpox, can induce brain swelling, pneumonia, hepatitis, meningitis, shingles and chickenpox in a small number of people whose immune systems are compromised, as well as in some patients whose have normal immune functioning. The committee also found that six vaccines — MMR, varicella, influenza, hepatitis B, meningococcal and tetanus — can trigger anaphylaxis, an allergic reaction that can appear shortly after an injection.
“Certainly, some vaccines result in adverse effects that must be acknowledged,” the authoring committee noted in the report.
Of the few adverse effects found to be caused by vaccines, most are “very rare or very mild,” the committee noted.
The committee also concluded that certain vaccines are not linked to some specific conditions. For example, the MMR vaccine does not cause Type 1 diabetes, nor does it cause autism. The evidence also shows that the flu shot does not cause Bell’s palsy or trigger asthma. Suggestions that vaccines can lead to such health problems have contributed to parental concerns about immunization for their children.
“The findings should be reassuring to parents that few health problems are clearly connected to immunizations, and these effects occur relatively rarely,” Clayton said.
For more information or to download “Adverse Effects of Vaccines: Evidence and Causality,” visit www.iom.edu.
- Copyright The Nation’s Health, American Public Health Association