Study Shows No Connection Between MMR Vaccine and Autism, GI Disturbances

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Title: Study Shows No Connection Between MMR Vaccine and Autism, GI Disturbances
URL: http://www.pslgroup.com/dg/22ACA6.htm
Doctor's Guide
September 4, 2008

NEW YORK -- September 4, 2008 -- In a case-controlled study, the presence of measles virus RNA was no more likely in children with autism and gastrointestinal (GI) disturbances than in children with only GI disturbances. Furthermore, GI symptom and autism onset were unrelated to measles, mumps, and rubella (MMR) vaccine timing. Study findings are reported in the September 4 issue of the Public Library of Science.

In 1998, a report of the presence of measles virus RNA in intestinal tissue from children with autism spectrum disorders and GI disturbances (Wakefield AJ et al. Lancet. 1998;351:637-641) resulted in public concern over the safety of MMR vaccine.

Although epidemiological investigations found no associations between MMR vaccine and autism, no subsequent studies tested for the presence of viral RNA in GI tissues of children with autism and GI disturbances or examined the temporal relationship of MMR, GI disturbances, and autism.

Failure to have done so may have contributed to the persistent concerns that have influenced vaccine acceptance rates, resulting in outbreaks of measles.

Researchers from Columbia University's Mailman School of Public Health, Center for Infection and Immunity, New York, New York; the Centers for Disease Control and Prevention, Atlanta, Georgia; Massachusetts General Hospital, Boston, Massachusetts; and Trinity College, Dublin, Ireland, evaluated bowel tissues from 25 children with autism and GI disturbances and 13 children with GI disturbances alone.

Using real-time reverse transcription (RT)-PCR for the presence of measles virus RNA, samples were analysed in 3 laboratories blinded to diagnosis, including 1 wherein the original findings suggesting a link between measles virus and autism had been reported.

"Our results are inconsistent with a causal role for MMR vaccine as a trigger or exacerbator of either GI difficulties or autism," said coauthor Mady Hornig, MD, Center for Infection and Immunity, Mailman School of Public Health.

"The work reported here eliminates the remaining support for the hypothesis that autism with GI complaints is related to MMR vaccine exposure. We found no relationship between the timing of MMR vaccine and the onset of either GI complaints or autism."

Analysis in all 3 laboratories found 2 biopsy samples with measles virus RNA; 1 from a boy in the autism/GI group and the other from a boy in the control group, showing that the presence of measles virus sequences was not associated with an autism diagnosis (autism/GI group, 4%; control, 8%).

The temporal order of onset of GI episodes and autism relative to timing of MMR vaccine administration was examined as well. If MMR is causally related to either GI disturbances or autism, it should precede their onset.

Analysis indicated no role for MMR vaccine in either the pathogenesis of autism or GI dysfunction. Only 5 of 25 subjects (20%) had received MMR vaccine before the onset of GI complaints and had also had onset of GI episodes before the onset of autism.

"Over 20 epidemiologic studies have reported no temporal relationship between MMR vaccine and autism; however, no published studies from other research groups have addressed whether measles virus RNA is present in the bowel of autistic children with GI disturbances," said coauthor W. Ian Lipkin, Center for Infection and Immunity, Mailman School of Public Health.

"Here we report results of independent, blinded testing in this particular subgroup for the presence of measles virus RNA in bowel tissues."

He adds that "the study design process was a critical piece, as there is still so much public concern over the safety of the MMR vaccine. For this reason, we involved the autism parent/advocacy community as we designed the study to ensure that all issues were being addressed.

"We are hopeful that this process of community engagement will build important partnerships among members of the autism community, physicians, public health agencies, and clinical researchers; serve as a paradigm for the conduct of future studies to understand the causes of this disorder; and facilitate the rapid communication of clinically relevant scientific findings to the broader community."

SOURCE: Columbia University's Mailman School of Public Health

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