title: Adverse events following vaccination with an inactivated, Vero cell culture-derived Japanese encephalitis vaccine in the United States, 2009-2012.
abstract: BACKGROUND
  In March 2009, the U.S. Food and Drug Administration licensed an inactivated, Vero cell culture-derived Japanese encephalitis vaccine (JE-VC [Ixiaro]) for use in adults. The vaccine was licensed based on clinical trial safety data in 3558 JE-VC recipients. It is essential to monitor post-licensure surveillance data to evaluate the safety of JE-VC because rare adverse events may not be detected until the vaccine is administered to a larger population.
  
  
  METHODS
  We reviewed adverse events reported to the U.S. Vaccine Adverse Event Reporting System (VAERS) for adults (≥17 years) who received JE-VC from May 2009 through April 2012. Adverse event reporting rates were calculated using 275,848 JE-VC doses distributed.
  
  
  RESULTS
  Over the 3 year period, 42 adverse events following vaccination with JE-VC were reported to VAERS for an overall reporting rate of 15.2 adverse events per 100,000 doses distributed. Of the 42 total reports, 5 (12%) were classified as serious for a reporting rate of 1.8 per 100,000 doses distributed; there were no deaths. Hypersensitivity reactions (N=12) were the most commonly reported type of adverse event, with a rate of 4.4 per 100,000 doses distributed; no cases of anaphylaxis were reported. Three adverse events of the central nervous system were reported (one case of encephalitis and two seizures) for a rate of 1.1 per 100,000; all occurred after receipt of JE-VC with other vaccines.
  
  
  CONCLUSIONS
  These post-marketing surveillance data suggest a good safety profile for JE-VC consistent with findings from pre-licensure clinical trials. Post-licensure safety data should continue to be monitored for any evidence of rare serious or neurologic adverse events.
authors.affiliation: Arboviral Diseases Branch, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, United States. Electronic address: irabe@cdc.gov.
authors.forename: Ingrid B
authors.initials: IB
authors.lastname: Rabe
authors.affiliation: Immunization Safety Office, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30333, United States.
authors.forename: Elaine R
authors.initials: ER
authors.lastname: Miller
authors.affiliation: Arboviral Diseases Branch, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, United States.
authors.forename: Marc
authors.initials: M
authors.lastname: Fischer
authors.affiliation: Arboviral Diseases Branch, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, United States.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hills
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002522:Chlorocebus aethiops; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology* / Q000473:pathology*; D004672:Encephalitis, Japanese / Q000517:prevention & control*; D005260:Female; D006801:Humans; D022321:Japanese Encephalitis Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000302:isolation & purification; D008297:Male; D008875:Middle Aged; D011358:Product Surveillance, Postmarketing; D013678:Technology, Pharmaceutical; D014481:United States; D014611:Vaccination / Q000009:adverse effects*; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000302:isolation & purification; D014709:Vero Cells; D055815:Young Adult
chemical_list: D022321:Japanese Encephalitis Vaccines; D015164:Vaccines, Inactivated
keywords: Japanese encephalitis vaccines; Public health surveillance; United States; Vaccines