{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,28]],"date-time":"2026-01-28T21:01:23Z","timestamp":1769634083996,"version":"3.49.0"},"reference-count":31,"publisher":"American Academy of Pediatrics (AAP)","issue":"5","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2003,11,1]]},"abstract":"<jats:p>Objective. Acellular pertussis vaccines were introduced with the promise of an improved safety profile compared with whole-cell vaccines. In 1997\u20131998, 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.<\/jats:p><jats:p>Methods. Active surveillance was performed between 1995 and 2001 by the Immunization Monitoring Program\u2013Active 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.<\/jats:p><jats:p>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\u20131996 and 1998\u20132001. There was a 60% to 67% reduction in HHEs associated with pertussis-containing vaccines between the same time periods, depending on case definition.<\/jats:p><jats:p>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.<\/jats:p>","DOI":"10.1542\/peds.112.5.e348","type":"journal-article","created":{"date-parts":[[2004,8,14]],"date-time":"2004-08-14T00:43:47Z","timestamp":1092444227000},"page":"e348-e348","source":"Crossref","is-referenced-by-count":81,"title":["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"],"prefix":"10.1542","volume":"112","author":[{"given":"Nicole","family":"Le Saux","sequence":"first","affiliation":[{"name":"Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nicholas J.","family":"Barrowman","sequence":"additional","affiliation":[{"name":"Chalmers Research Group, Children\u2019s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dorothy L.","family":"Moore","sequence":"additional","affiliation":[{"name":"Montreal Children\u2019s Hospital, McGill University Health Centre, Montreal, Quebec, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sharon","family":"Whiting","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David","family":"Scheifele","sequence":"additional","affiliation":[{"name":"British Columbia\u2019s Children\u2019s Hospital, Vancouver, British Columbia, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Scott","family":"Halperin","sequence":"additional","affiliation":[{"name":"IWK Health Center, Halifax, Nova Scotia, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"name":"for Members of the Canadian Paediatric Society\/ Health Canada Immunization Monitoring Program\u2013Active (IMPACT)","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"417","published-online":{"date-parts":[[2003,11,1]]},"reference":[{"key":"2021120820290993000_R1","doi-asserted-by":"crossref","unstructured":"Wortis N, Strebel PM, Wharton M, et al. Pertussis deaths: report of 23 cases in the United States, 1992 and 1993. Pediatrics. 1996; 97: 607\u2013612","DOI":"10.1542\/peds.97.5.607"},{"key":"2021120820290993000_R2","doi-asserted-by":"crossref","unstructured":"Miller E. Collapse reactions after whole cell pertussis vaccination. Pertussis remains a bigger risk than collapse after vaccination. BMJ. 1998; 316: 876","DOI":"10.1136\/bmj.316.7135.876"},{"key":"2021120820290993000_R3","unstructured":"Centers for Disease Control and Prevention. Pertussis deaths\u2014United States, 2000. MMWR Morb Mortal Wkly Rep. 2002; 51: 616\u2013618"},{"key":"2021120820290993000_R4","doi-asserted-by":"crossref","unstructured":"De Serres G, Shadmani R, Duval B, et al. Morbidity of pertussis in adolescents and adults. J Infect Dis. 2000; 182: 174\u2013179","DOI":"10.1086\/315648"},{"key":"2021120820290993000_R5","doi-asserted-by":"crossref","unstructured":"Duclos P, Olive JM. Invited commentary: pertussis, a forgotten killer. 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