title: Waning intestinal immunity after vaccination with oral poliovirus vaccines in India.
abstract: BACKGROUND
  The eradication of wild-type polioviruses in areas with efficient fecal-oral transmission relies on intestinal mucosal immunity induced by oral poliovirus vaccine (OPV). Mucosal immunity is thought to wane over time but the rate of loss of protection has not been examined.
  
  
  METHODS
  We examined the degree and duration of intestinal mucosal immunity in India by measuring the prevalence of vaccine poliovirus in stool samples collected 4-28 days after a "challenge" dose of OPV among 47 574 children with acute flaccid paralysis reported during 2005-2009.
  
  
  RESULTS
  Previous vaccination with OPV was protective against excretion of vaccine poliovirus after challenge, but the odds of excretion increased significantly with the time since the child was last exposed to an immunization activity (odds ratio, 1.39 [95% confidence interval .99-1.97], 2.04 [1.28-3.25], and 1.31 [1.00-1.70] comparing ≥6 months with 1 month ago for serotypes 1, 2, and 3, respectively). Vaccine administered during the high season for enterovirus infections (April-September) was significantly less likely to result in excretion, especially in northern states (odds ratio, 0.57 [95% confidence interval, .50-.65], 0.58 [.41-.81], and 0.48 [.40-.57] for serotypes 1, 2, and 3).
  
  
  CONCLUSIONS
  Infection with OPV (vaccine "take") is highly seasonal in India and results in intestinal mucosal immunity that appears to wane significantly within a year of vaccination.
authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom. n.grassly@imperial.ac.uk
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Grassly
authors.forename: Hamid
authors.initials: H
authors.lastname: Jafari
authors.forename: Sunil
authors.initials: S
authors.lastname: Bahl
authors.forename: Raman
authors.initials: R
authors.lastname: Sethi
authors.forename: Jagadish M
authors.initials: JM
authors.lastname: Deshpande
authors.forename: Chris
authors.initials: C
authors.lastname: Wolff
authors.forename: Roland W
authors.initials: RW
authors.lastname: Sutter
authors.forename: R Bruce
authors.initials: RB
authors.lastname: Aylward
mesh_terms: D002675:Child, Preschool; D005243:Feces / Q000821:virology; D005260:Female; D006801:Humans; D018928:Immunity, Mucosal / Q000276:immunology; D007194:India; D007223:Infant; D007413:Intestinal Mucosa / Q000276:immunology*; D016015:Logistic Models; D008297:Male; D011051:Poliomyelitis / Q000276:immunology* / Q000517:prevention & control* / Q000821:virology; D017955:Poliovirus / Q000276:immunology* / Q000302:isolation & purification / Q000502:physiology; D011055:Poliovirus Vaccine, Oral / Q000276:immunology*; D012621:Seasons; D013997:Time Factors; D014611:Vaccination; D017201:Virus Shedding
chemical_list: D011055:Poliovirus Vaccine, Oral