title: Risk of intussusception after monovalent rotavirus vaccination.
abstract: BACKGROUND
  Although current rotavirus vaccines were not associated with an increased risk of intussusception in large trials before licensure, recent postlicensure data from international settings suggest the possibility of a small increase in risk of intussusception after monovalent rotavirus vaccination. We examined this risk in a population in the United States.
  
  
  METHODS
  Participants were infants between the ages of 4 and 34 weeks who were enrolled in six integrated health care organizations in the Vaccine Safety Datalink (VSD) project. We reviewed medical records and visits for intussusception within 7 days after monovalent rotavirus vaccination from April 2008 through March 2013. Using sequential analyses, we then compared the risk of intussusception among children receiving monovalent rotavirus vaccine with historical background rates. We further compared the risk after monovalent rotavirus vaccination with the risk in a concurrent cohort of infants who received the pentavalent rotavirus vaccine.
  
  
  RESULTS
  During the study period, 207,955 doses of monovalent rotavirus vaccine (including 115,908 first doses and 92,047 second doses) were administered in the VSD population. We identified 6 cases of intussusception within 7 days after the administration of either dose of vaccine. For the two doses combined, the expected number of intussusception cases was 0.72, resulting in a significant relative risk of 8.4. For the pentavalent rotavirus vaccine, 1,301,810 doses were administered during the study period, with 8 observed intussusception cases (7.11 expected), for a nonsignificant relative risk of 1.1. The relative risk of chart-confirmed intussusception within 7 days after monovalent rotavirus vaccination, as compared with the risk after pentavalent rotavirus vaccination, was 9.4 (95% confidence interval, 1.4 to 103.8). The attributable risk of intussusception after the administration of two doses of monovalent rotavirus vaccine was estimated to be 5.3 per 100,000 infants vaccinated.
  
  
  CONCLUSIONS
  In this prospective postlicensure study of more than 200,000 doses of monovalent rotavirus vaccine, we observed a significant increase in the rate of intussusception after vaccination, a risk that must be weighed against the benefits of preventing rotavirus-associated illness. (Funded by the Centers for Disease Control and Prevention.).
authors.affiliation: From the Centers for Disease Control and Prevention, Immunization Safety Office, Atlanta (E.S.W., J.B., J.D., C.V., F.D.); Marshfield Clinic Research Foundation, Marshfield, WI (E.A.B.); Center for Health Research, Kaiser Permanente Northwest, Portland, OR (S.I., A.N.); Vaccine Study Center, Kaiser Permanente Northern California, Oakland (N.P.K.); Kaiser Permanente Colorado, Aurora (J.M.G.); Kaiser Permanente Southern California, Pasadena (S.J.J.); and Group Health Research Institute, Seattle (L.A.J.).
authors.forename: Eric S
authors.initials: ES
authors.lastname: Weintraub
authors.forename: James
authors.initials: J
authors.lastname: Baggs
authors.forename: Jonathan
authors.initials: J
authors.lastname: Duffy
authors.forename: Claudia
authors.initials: C
authors.lastname: Vellozzi
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
authors.forename: Stephanie
authors.initials: S
authors.lastname: Irving
authors.forename: Nicola P
authors.initials: NP
authors.lastname: Klein
authors.forename: Jason M
authors.initials: JM
authors.lastname: Glanz
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Jacobsen
authors.forename: Allison
authors.initials: A
authors.lastname: Naleway
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Jackson
authors.forename: Frank
authors.initials: F
authors.lastname: DeStefano
mesh_terms: D015331:Cohort Studies; D006801:Humans; D007117:Immunization, Secondary; D007223:Infant; D007443:Intussusception / Q000453:epidemiology / Q000209:etiology*; D016012:Poisson Distribution; D012306:Risk; D022243:Rotavirus Vaccines / Q000009:adverse effects*; D014481:United States; D014613:Vaccines, Attenuated / Q000009:adverse effects
chemical_list: C492535:RotaTeq; D022243:Rotavirus Vaccines; D014613:Vaccines, Attenuated