# 5884
It is no secret that vaccines, like all drugs and medications, can cause adverse effects in some subset of their recipients. In very rare instances, those side effects can be serious, although most of the time they are minor and transient.
Today, the IOM (Institute of Medicine) released a massive (660+ page) analysis and review of more than 1,000 previous studies that looked at suspected health effects related to eight types of vaccination.
- chickenpox
- influenza
- hepatitis B
- human papillomavirus
- diphtheria, tetanus and pertussis (DTaP)
- measles, mumps and rubella (MMR)
- hepatitis A
- meningococcal disease
While a small number of rare adverse effects were causally linked some to specific vaccines – particularly among immunocompromised recipients of live-virus vaccines – the news is overwhelmingly positive.
First some excerpts (slighted reformatted for readability) from the press release by the National Academy of Sciences, then the link where you can download a prepublication PDF version for free.
Public release date: 25-Aug-2011
Few health problems are caused by vaccines, IOM report finds
WASHINGTON — An analysis of more than 1,000 research articles concluded that few health problems are caused by or clearly associated with vaccines. A committee of experts convened by the Institute of Medicine to review the scientific literature on possible adverse effects of vaccines found convincing evidence of 14 health outcomes -- including seizures, inflammation of the brain, and fainting -- that can be caused by certain vaccines, although these outcomes occur rarely. It also found indicative though less clear data on associations between specific vaccines and four other effects, such as allergic reactions and temporary joint pain. In addition, the evidence shows there are no links between immunization and some serious conditions that have raised concerns, including Type 1 diabetes and autism. The data were inadequate to reach conclusions about other suggested adverse effects.
<SNIP>
Convincing evidence shows that the measles-mumps-rubella (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 also can produce a rare form of brain inflammation in some people with severe immune system deficiencies.
In a minority of patients, the varicella vaccine against chickenpox can induce brain swelling, pneumonia, hepatitis, meningitis, shingles, and chickenpox in immunocompromised patients as well as some who apparently have competent immune function, the committee found.
The majority of these problems have occurred in individuals with immunodeficiencies, which increase individuals' susceptibility to the live viruses used in MMR and varicella.
Six vaccines -- MMR, varicella, influenza, hepatitis B, meningococcal, and the tetanus-containing vaccines -- can trigger anaphylaxis, an allergic reaction that appears shortly after injection. And, in general, the injection of vaccines can trigger fainting and inflammation of the shoulder, the committee noted.
The evidence suggests that certain vaccines can lead to four other adverse effects, although the data on these links are not as convincing, the report says. The MMR vaccine appears to trigger short-term joint pain in some women and children. Some people can experience anaphylaxis after receiving the HPV vaccine. And certain influenza vaccines used abroad have resulted in a mild, temporary oculo-respiratory syndrome characterized by conjunctivitis, facial swelling, and mild respiratory symptoms.
The committee's review also concluded that certain vaccines are not linked to four specific conditions. The MMR vaccine and diphtheria-tetanus-acellular pertussis (DTaP) do not cause Type 1 diabetes, and the MMR vaccine does not cause autism, according to the results of several studies. The evidence shows that the flu shot does not cause Bell's palsy or exacerbate asthma. Suggestions that vaccines can lead to these serious health problems have contributed to parental concerns about immunization for their children.
There are, of course, many instances where there is simply insufficient evidence to decide – one way or the other – whether a vaccine might have contributed to some rarely reported side effect.
All drugs can have side effects.
And there is always a risk-reward calculation that we must all make when deciding to take medications, whether it be a vaccine, an antibiotic, or an over-the-counter headache remedy.
The evidence of the rewards that vaccines provide can be easily seen by the dramatic drop in vaccine-preventable illnesses in countries where they are widely used.
The chart below (source: CDC) shows the remarkable effectiveness of the measles vaccine campaign.
Vaccine critics are unlikely to be assuaged by today’s IOM report, but for those willing to look at the available evidence, this report should be reassuring.
You can access this report online, or download it as an 18MB PDF file from the The National Academies Press.
Adverse Effects of Vaccines:
Evidence and Causality
Status: Prepublication Available
Size: 800 pages, 6 x 9
Publication Year:2011
Description
Immunizations are a cornerstone of the nation's efforts to protect people from a host of infectious diseases. Though generally very rare or very minor, there are side effects, or "adverse effects," associated with some vaccines. The IOM reviewed a list of adverse events associated with eight vaccines to evaluate the scientific evidence about the event-vaccine relationship. Using epidemiologic and mechanistic evidence, the committee developed 158 causality conclusions, assigning each relationship between a vaccine and an adverse health problem to one of four causation categories. Overall, the IOM committee concludes that few health problems are caused by or clearly associated with vaccines.
For more coverage on today’s IOM report, you may wish to check out the following media stories.
Vaccines given a clean bill of health - Nature.com
Report Finds Few Health Problems Tied to Vaccines - Wall Street Journal (blog
U.S.mandated report finds vaccines safe for kids -USA Today
