Few health problems are caused by or clearly associated with vaccines, according to a new analysis of more than 1,000 research articles by the Institute of Medicine.
The report, released Aug. 25, comes after a review by an IOM committee of scientific literature on possible adverse effects of vaccines. The review is the first comprehensive IOM study on vaccine safety in 17 years.
The IOM committee – made up of 16 pediatricians, internists and immunologists – assessed more than 1,000 studies issued between April 2009 and March 2011. Specifically, the committee looked at the possible effects of eight vaccines given to children or adults – measles-mumps-rubella, chickenpox, influenza, hepatitis A, hepatitis B, human papillomavirus, diphtheria-tetanus-pertussis and meningococcal.
The report, “Adverse Effects of Vaccines: Evidence and Causality,” found 14 health outcomes – including seizures, inflammation of the brain and fainting – that can be caused by these vaccines, but noted that these outcomes rarely occur.
“It is a medical and public health fact that vaccines are important tools in preventing serious infectious diseases across the lifespan through infancy to adulthood,” Dr. Ellen Wright-Clayton, chairwoman of the IOM panel, said during a Sept. 1 briefing on the committee’s findings. “All health interventions, however, carry the possibility of risks, and vaccines are no exception.”
Wright-Clayton teaches law and pediatrics at Vanderbilt University and is the director for the Center for Biomedical Ethics and Society.
Fears that vaccines can lead to serious health problems like autism have contributed to parental concerns about immunization for their children.
But the committee’s review concluded that there are no direct links between certain vaccines and some serious conditions that have raised public concerns, including type 1 diabetes and autism. For example, the report found that the measles-mumps-rubella, or MMR, vaccine and diphtheria-tetanus-acellular pertussis do not cause type 1 diabetes, and the MMR vaccine does not cause autism.
The report also shows that the flu shot does not cause Bell's palsy or exacerbate asthma.
The MMR vaccine can lead to fever-triggered seizures in some individuals, although these effects are almost always without long-term consequences, the report says.
The MMR vaccine can also produce a rare form of brain inflammation in some people with severe immune system deficiencies. In a minority of patients, the varicella, or chickenpox, vaccine against can induce brain swelling, pneumonia, hepatitis, meningitis, shingles and chickenpox in patients with immune system deficiencies as well as some patients who apparently have competent immune function. Immunodeficiencies increase individuals' susceptibility to the live viruses used in MMR and varicella, making them more prone to having complications than those with normal immune systems.
Six vaccines – MMR, varicella, influenza, hepatitis B, meningococcal and the tetanus-containing vaccines – can trigger anaphylaxis, an allergic reaction that appears shortly after injection. In general, the injection of vaccines can trigger fainting and inflammation of the shoulder, the committee found.
The committee’s review suggests that certain vaccines can lead to four other adverse effects, although the data on these links are not very strong, according to the report. The MMR vaccine can trigger short-term joint pain in some women and children. With the HPV vaccine, some patients can experience allergic reactions. Certain influenza vaccines used abroad have resulted in mild adverse effects including facial swelling, pink eye and respiratory problems.
The committee was charged by the Health Resources and Services Administration to focus solely on analyzing the potential risks of immunizations. It did not examine information about the ratio of potential benefits to risks.
Read the full IOM report
here.
Email
Print
Reprints/Licensing
Comment