Decrease in Hospital Admissions for Febrile Seizures and Reports of Hypotonic-Hyporesponsive Episodes Presenting to Hospital Emergency Departments Since Switching to Acellular Pertussis Vaccine in Canada: A Report From IMPACT

Nicole Le Saux, MD^*, Nicholas J. Barrowman, PhD, Dorothy L. Moore, MD, PhD, Sharon Whiting, MD^*, David Scheifele, MD^|| and Scott Halperin, MD^¶ for Members of the Canadian Paediatric Society/ Health Canada Immunization Monitoring Program–Active (IMPACT)

^* Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada
Chalmers Research Group, Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
Montreal Children’s Hospital, McGill University Health Centre, Montreal, Quebec, Canada
^|| British Columbia’s Children’s Hospital, Vancouver, British Columbia, Canada
^¶ IWK Health Center, Halifax, Nova Scotia, Canada

Objective. Acellular pertussis vaccines were introduced with the promise of an improved safety profile compared with whole-cell vaccines. In 1997–1998, Canada adopted 1 combination acellular pertussis vaccine, having previously used 1 particular combination whole-cell pertussis vaccine. We hypothesized that the change would result in a decrease in hospitalization rates for seizures and reports of hypotonic-hyporesponsive episodes (HHEs) temporally related to pertussis vaccination.

Methods. Active surveillance was performed between 1995 and 2001 by the Immunization Monitoring Program–Active monitors at 12 hospitals using standard case definitions. Seizures had to occur within 72 hours after immunization with a pertussis-containing vaccine or 5 to 30 days after immunization with measles-mumps-rubella vaccine. HHE episodes had to occur within 48 hours of receipt of a pertussis-containing vaccine. Poisson regression models were used to compare the average number of monthly admissions for seizures and HHEs before and after introduction of the acellular pertussis vaccine.

Results. We found a 79% decrease in febrile seizures associated with receipt of pertussis vaccine but no significant decrease in febrile seizures temporally related to measles-mumps-rubella between 1995–1996 and 1998–2001. There was a 60% to 67% reduction in HHEs associated with pertussis-containing vaccines between the same time periods, depending on case definition.

Conclusions. The risks of febrile seizures and HHEs after pertussis-containing vaccine declined significantly with the introduction of acellular pertussis vaccine in Canada. Active surveillance systems are important for detecting trends in uncommon adverse events after routine immunizations.

A quote from researcher David Geier, MD, PhD: "We went to Atlanta," he continues, "to the CDC, and looked at the VSD [Vaccine Safety Data] data. There is  thimerosal-containing DTaP [diphtheria, tetanus and pertussis vaccine] and thimerosal-free DTaP, so we asked a question: Among children that got a minimum of  either three consecutive thimerosal-containing DTaPs or   three consecutive thimerosal-free DTaPs, was there a difference in the number of autism cases in the two groups? We found mega differences. More than 20 times higher. The rate of autism in the children that got more than three doses of thimerosal-containing DTaP  vaccines was much, much higher. Almost all the children that   have autism in that group were the ones that got the thimerosal-containing DTaP vaccine. The more  thimerosal the greater the cases of autism."
   --O'Meara KP. CDC Study Raises Level of Suspicion.
      http://www.insightmag.com/news/573542.html
 

 Posted on Wed, Nov. 08, 2006 by Sun Herald.com

http://www.sunherald.com/mld/sunherald/news/state/15957141.htm?template=contentModules/printstory.jsp

MSU studies safer vaccine
Current ones may damage

THE ASSOCIATED PRESS

STARKVILLE - Biologists at Mississippi State University are studying safer vaccines for whooping cough, which can sometimes lead to brain damage or death.

Lakshmi Pulakat and Nara Gavini head up a research team that discovered a mechanism in current vaccines that may trigger neurological damage among whooping cough patients.

Whooping cough is caused by the bacterium Bordetella pertussis, which produces various toxins upon infection, said Mary Hetrick, a member of the MSU research team and a biological sciences doctoral student.

"Neurological damage is a dangerous after-effect among patients suffering from whooping cough and also seems to affect infants vaccinated with DPT vaccine or acellular vaccine," said Hetrick.

Hetrick said Pulakat and Gavini "have identified a novel mechanism by which the pertussis toxin can exert its ill effects and contribute to brain damage.

Since this mechanism is significantly different from the conventional understanding of the action of pertussis toxin, this study provides new possibilities to generate safer acellular vaccines to combat whopping cough," she said.

 2006 The Sun Herald and wire service sources. All Rights Reserved.
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