Seems a bit like covering one’s tracks here. Seizures and Autism commonly go – hand in hand and can trigger serious health issues which lie dormant in the body.

Written and owned By Michael Smith, North American Correspondent, MedPage Today Published: March 14, 2008

Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston.

ATLANTA, March 14 — An apparent increased risk of febrile seizures has led the CDC to soften one of its recommendations on immunizing children against measles, mumps, rubella, and varicella with a combination vaccine.

The agency had said the combination tetravalent vaccine against the four diseases (ProQuad) was to be preferred over vaccination with a trivalent measles, mumps, and rubella vaccine at the same time as a separate varicella shot.

That preferential recommendation has been withdrawn. The agency’s Advisory Committee on Immunization Practices (ACIP) now says there should be no preference, the CDC said in the March 14 issue of Morbidity and Mortality Weekly Report.

The change comes after review of data from the Vaccine Safety Datalink, which monitors vaccine safety, as well as preliminary results from a post-licensing study conducted by Merck, which makes the tetravalent vaccine.

The Vaccine Safety Datalink, the CDC said, showed a signal of increased risk for seizure among children ages 12 to 23 months who were given the tetravalent vaccine, compared with those who got the trivalent vaccine.

The increased rates were seen seven to 12 days after vaccination.

Once the signal was seen, the agency said, analysts used the Vaccine Safety Datalink for a study comparing seizure rates among children who got the tetravalent vaccine and those who got a trivalent vaccine plus a varicella vaccine at the same visit.

The analysis included 43,353 children ages 12 to 23 months who received the tetravalent vaccine and 314,599 who received the trivalent vaccine and varicella vaccine at the same visit.

The researchers reviewed medical records to validate the diagnosis and used a multivariate logistic regression to adjust for age and influenza season, the CDC said.

Results of that analysis showed:

* A rate of nine febrile seizures per 10,000 vaccinations among recipients of the tetravalent vaccine.
* The rate was four per 10,000 vaccinations among those who got the trivalent vaccine along with the varicella vaccine.
* The adjusted odds ratio was 2.3, with a 95% confidence interval from 1.6 to 3.2, which was significant at P<0.0001.
* Of the 166 children who had febrile seizures after vaccination and had hospitalization information available, 26 (or 16%) were admitted to a hospital.
* There were no deaths.

The advisory committee was told that interim data from the Merck post-licensing study showed a similar relative risk for seizure, although the difference did not reach statistical significance. Only about half of the final sample size needed was available for the analysis.

Neither study looked at the risk of a febrile seizure after the second recommended dose of the vaccine, at ages four through six years.

The CDC noted that the tetravalent vaccine is currently in short supply in the U.S., because of manufacturing problems not related to safety, and is not expected to be widely available before 2009.

The agency also said that febrile seizures are not uncommon in children and generally have an excellent prognosis.

Additional source: CDC
Source reference:
CDC “Update: Recommendations from the Advisory Committee on Immunization Practices (ACIP) regarding administration of combination MMRV vaccine” MMWR 2008; 57(10): 258-60.

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