title: Intussusception and Monovalent Rotavirus Vaccination in Singapore: Self-Controlled Case Series and Risk-Benefit Study.
abstract: OBJECTIVE
  To investigate the association between monovalent human rotavirus vaccine (RV1) and intussusception among Asian infants and the impact of older age of vaccination. To perform risk-benefit analysis of RV1 vaccination programs in Singapore.
  
  
  METHODS
  We performed a self-controlled case series by extracting intussusception cases in infants aged <12 months from hospital databases (2005-2012) and with vaccination histories from a national immunization registry. Relative incidences were calculated by comparing incidence during defined risk periods after vaccination with times outside these periods. In the risk benefit analysis, we estimated excess intussusception hospitalization in relation to the number of infants vaccinated for hypothetical vaccination coverage scenarios.
  
  
  RESULTS
  There were 86 infants hospitalized with intussusception; 20 cases had received at least 1 dose of RV1. Nearly all (19) had received their first dose at age >12 weeks old. The age-adjusted relative incidence of intussusception in the 1- to 7-day period post dose one was 8.36 (95% CI 2.42-28.96). Of all childhood hospitalizations because of rotavirus, 71% (570 cases) could be prevented with 90% vaccination coverage. There would be approximately 1 excess intussusception case per 65,000 infants vaccinated.
  
  
  CONCLUSIONS
  Risk of intussusception increases about 8-fold during 1-7 days after receipt of first dose RV1 in infants of Chinese, Malay, and Indian ethnicity in Singapore, Asia. High vaccine coverage program in Singapore would be beneficial with only a low risk of excess intussusception. The relative risk of intussusception post-RV1 vaccination is not higher in Asia despite differences in background intussusception incidence compared with US and Australia, or older age of vaccination.
authors.affiliation: Department of Clinical Epidemiology, Communicable Disease Center, Tan Tock Seng Hospital, Singapore. Electronic address: cheefu.yung@gmail.com.
authors.forename: Chee-Fu
authors.initials: CF
authors.lastname: Yung
authors.affiliation: Department of Clinical Epidemiology, Communicable Disease Center, Tan Tock Seng Hospital, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Faculty of Science, Technology and Engineering, La Trobe University, Melbourne, Australia.
authors.forename: Siew Pang
authors.initials: SP
authors.lastname: Chan
authors.affiliation: Vigilance Branch, Health Products Regulation Group, Health Sciences Authority, Singapore.
authors.forename: Sally
authors.initials: S
authors.lastname: Soh
authors.affiliation: Department of Clinical Epidemiology, Communicable Disease Center, Tan Tock Seng Hospital, Singapore.
authors.forename: Adriana
authors.initials: A
authors.lastname: Tan
authors.affiliation: Department of Pediatric Medicine, KK Women's and Children's Hospital, Singapore.
authors.forename: Koh Cheng
authors.initials: KC
authors.lastname: Thoon
mesh_terms: D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007223:Infant; D007443:Intussusception / Q000453:epidemiology*; D008297:Male; D012042:Registries; D018570:Risk Assessment; D012400:Rotavirus Infections / Q000453:epidemiology / Q000517:prevention & control; D022243:Rotavirus Vaccines / Q000009:adverse effects*; D012846:Singapore / Q000453:epidemiology; D014611:Vaccination / Q000706:statistics & numerical data*
chemical_list: D022243:Rotavirus Vaccines