Childhood vaccines do not raise brain disease risk

Childhood vaccination against whooping cough (also known as pertussis) and measles is not associated with an increased risk for encephalopathy, a disease of the brain, according to a new report.

Encephalopathy or encephalitis have been reported to occur with increased frequency after receipt of whole-cell pertussis (DTP) vaccine or combined measles-mumps-rubella (MMR) vaccine, but the association remains controversial.

Paula Ray from Kaiser Permanente Vaccine Study Center, Oakland, California and colleagues used data from 4 study sites to re-evaluate whether whole-cell pertussis and measles vaccination are associated with encephalopathy or encephalitis. In all, 452 cases of encephalopathy were identified in records from more than 2 million children.

At no time period studied were patients with encephalopathy more likely than controls to have received DTP or MMR vaccine, the authors report. In fact, patients with encephalopathy were significantly less likely than controls to have received DTP vaccine in the prior 60 or 90 days.

When only the patients without a known cause of encephalopathy were considered, there was a slightly but insignificantly higher likelihood of having received DTP, the results indicate.

Similarly, the researchers note, children with neurologic disease of unknown or suspected but unconfirmed cause were numerically (but not significantly) more likely to have received MMR vaccine in the prior 90 days.

“Although this study is large, encephalopathy is rare,” the authors observe, “and thus it is not possible to exclude completely a small increase in the risk of encephalopathy after DTP or MMR vaccination.”

“However,’ they conclude, “if such an increased risk exists, the absolute risk is extremely small and it is much lower after vaccination than after pertussis or measles.”

SOURCE: The Pediatric Infectious Disease Journal, September 2006.

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