Confessions of a Quackbuster

This blog deals with healthcare consumer protection, and is therefore about quackery, healthfraud, chiropractic, and other forms of so-Called "Alternative" Medicine (sCAM).

Thursday, October 20, 2005

MMR Vaccine is Safe, International Team Affirms

MMR Vaccine is Safe, International Team Affirms

By Neil Osterweil, Senior Associate Editor, MedPage Today
Reviewed by Robert Jasmer, MD; Assistant Professor of Medicine, University of California, San Francisco
October 19, 2005
Also covered by: Newsday

MedPage Today Action Points

* Reassure concerned parents that in the most comprehensive review to date, an international team has found no credible scientific evidence to suggest that the MMR vaccine could cause autism or inflammatory bowel disease.

* Inform parents that in the review, MMR vaccination was associated with benign thrombocytopenic purpura, parotitis, joint and limb complaints, and febrile convulsions within two weeks of vaccination.

* Emphasize to parents the serious risks, including death and disability, that can occur in children who are not vaccinated against mumps, measles and rubella.

ALESSANDRIA, Italy, Oct. 19 - The only serious harm associated with the mumps-measles-rubella (MMR) vaccine is the risk to the health of children who aren't vaccinated, pronounced an international team of investigators today.

"In particular we conclude that all the major unintended events, such as triggering Crohn's disease or autism, were suspected on the basis of unreliable evidence," said Vittorio Demicheli, M.D., of the Servizo Sovrazonale di Epidemiologia here and colleagues in a systematic review from the Cochrane Collaboration.

"Mumps, measles and rubella are serious diseases that can lead to potentially fatal illness, disability and death." Dr. Demicheli and colleagues wrote. "Measles, mumps and rubella are particularly prevalent in developing countries where vaccination programs are inconsistent and the mortality rate from disease is high. In developed countries, however, mumps, measles and rubella are now rare, due to large-scale vaccination programs."

Doubts about the safety of the MMR vaccine spring from a single study of 12 patients published by Andrew J. Wakefield, M.D., and colleagues in The Lancet in 1998. In that study, the authors reported that "onset of behavioral symptoms was associated, by the parents, with measles, mumps, and rubella vaccination in eight of the 12 children, with measles infection in one child, and otitis media in another."

The Wakefield paper also found an associated between MMR and gastrointestinal disease. The study was retracted in 2004 by 10 of the original 13 authors.

In the current review, Dr. Demicheli and colleagues conducted a systematic literature review looking for evidence of MMR vaccine effectiveness and adverse events associated with its use. They identified 139 studies, 31 of which were deemed to be of sufficiently high quality to rule out bias or error.

The studies included comparative prospective or retrospective trials testing the effects of MMR compared with placebo, no treatment, or to a combination of measles, mumps and rubella antigens on healthy children up to 15 years old.

The investigators found that the vaccine was associated with a lower rate of upper respiratory tract infections, higher rate of irritability, and similar rate of other adverse effects compared to placebo.

They also found positive associations between MMR and benign thrombocytopenic purpura, parotitis, joint and limb complaints, and febrile convulsions within two weeks of vaccination.

In addition, versions of the vaccine containing the Urabe strain of mumps, but not the more widely used Jeryl Lynn strain, were associated with aseptic meningitis.

In contrast, the reviewers found no credible evidence of an association between MMR vaccination and Crohn's disease, ulcerative colitis, or autism.

Although they were unable to identify MMR effectiveness studies with clear clinical endpoints, the overwhelming evidence of elimination or radical reduction of the targeted diseases via mass immunization campaigns stands as proof that the vaccine works as intended, they wrote.

"The safety record of MMR is possibly best attested by its almost universal use," Dr. Demicheli and colleagues wrote. "Its evaluation cannot be divorced from its effectiveness and the importance of the target diseases. As such, MMR remains an important preventive global intervention."

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