Vaccine protection of bangladeshi infants and young children against cholera: Implications for vaccine deployment and person-to-person transmission

Mohammad Ali, Michael Emch, Mohammad Yunus, David Sack, Anna Lena Lopez, Jan Holmgren, John Clemens

Research output: Contribution to journalArticle

Abstract

BACKGROUND: Killed oral cholera vaccines are internationally licensed for older children and adults, but not for infants and young children. We investigated whether mass immunization of older children and adults can confer herd protection to children too young to be vaccinated. METHODS: We analyzed the first year of surveillance of an individually randomized, placebo-controlled trial of killed oral cholera vaccines in 89,596 older Bangladeshi children and adult women. Vaccine herd protection of children less than 2 years of age, who were too young to participate in the trial, was evaluated by determining whether the incidence of cholera during the first year of follow-up of this age group was lower in residential clusters with higher levels of vaccine coverage than in clusters with lower levels of vaccine coverage. RESULTS: Vaccine coverage of the targeted population ranged from 4% to 65% in different clusters. The incidence (cases per 1000) of cholera among children less than 2 years of age ranged from 18.9 in clusters in the lowest quintile of vaccine coverage to 8.6 in clusters in the highest quintile (P = 0.004 for the inverse association between vaccine coverage and risk of cholera) Vaccine coverage of adult women (relative risk of cholera = 0.95 for each percent increase in vaccine coverage; 95% confidence interval: 0.92-0.99; P < 0.01), but not of older children, was independently associated with a lower risk of cholera in children less than 2 years of age. CONCLUSIONS: Vaccination of older age groups was associated with protection of children too young to be vaccinated. The pronounced herd protection of young children associated with vaccination of adult women suggests that adult women may play a prominent role in the transmission of cholera to young children in this setting.

Original languageEnglish (US)
Pages (from-to)33-37
Number of pages5
JournalPediatric Infectious Disease Journal
Volume27
Issue number1
DOIs
StatePublished - Jan 2008

Keywords

  • Cholera
  • Cholera vaccines
  • Herd protection

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Microbiology (medical)
  • Infectious Diseases

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