title: Post licensure surveillance of influenza vaccines in the Vaccine Safety Datalink in the 2013-2014 and 2014-2015 seasons.
abstract: The changes in each year in influenza vaccine antigenic components as well as vaccine administration patterns may pose new risks of adverse events following immunization (AEs). To evaluate the safety of influenza vaccines annually administered to people ≥ 6 months, we conducted weekly post licensure surveillance for seven pre-specified adverse events following receipt of influenza vaccines during the 2013-2014 and 2014-2015 seasons in the Vaccine Safety Datalink (VSD).
  
  
  
  We used both a historically-controlled cohort design with the Poisson-based maximized sequential probability ratio test (maxSPRT) and a self-controlled risk interval (SCRI) design with the binomial-based maxSPRT. For each adverse event outcome, we defined the risk interval on the basis of biologic plausibility and prior literature. For the historical cohort design, numbers of expected adverse events were calculated from the prior seven seasons, adjusted for age and site. For the SCRI design, a comparison window was defined either before vaccination or after vaccination, depending on each specific outcome.
  
  
  
  An elevated risk of febrile seizures 0-1 days following trivalent inactivated influenza vaccine (IIV3) was identified in children aged 6-23 months during the 2014-2015 season using the SCRI design. We found the relative risk (RR) of febrile seizures following concomitant administration of IIV3 and PCV13 was 5.3 with a 95% CI 1.87-14.75. Without concomitant PCV 13 administration, the estimated risk decreased and was no longer statistically significant (RR: 1.4; CI: 0.54 - 3.61).
  
  
  
  No increased risks, other than for febrile seizures, were identified in influenza vaccine safety surveillance during 2013-2014 and 2014-2015 seasons in the VSD. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Rongxia
authors.initials: R
authors.lastname: Li
authors.affiliation: Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Brock
authors.initials: B
authors.lastname: Stewart
authors.affiliation: Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: McNeil
authors.affiliation: Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Duffy
authors.affiliation: Group Health Research Institute, Seattle, WA, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Nelson
authors.affiliation: Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA.
authors.forename: Alison Tse
authors.initials: AT
authors.lastname: Kawai
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, CA, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Baxter
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, WI, USA.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
authors.affiliation: Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Weintraub
mesh_terms: D000293:Adolescent; D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems; D000367:Age Factors; D000368:Aged; D000956:Antigens, Viral / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D011358:Product Surveillance, Postmarketing; D012306:Risk; D012621:Seasons; D003294:Seizures, Febrile / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000956:Antigens, Viral; D007252:Influenza Vaccines
keywords: PCV13; febrile seizures; pharmacoepidemiology; vaccine safety