Vaccine effectiveness against clinical cholera in Huang Mai and Thanh Xuan following the mass vaccination campaign in 2008 (vaccinated districts).

Vaccinated was defined as having received one or two doses of vaccine.Crude Protective Efficacy (PE) = 54% (95% CI −31% to 84%; p-value = 0.144).Adjusted PE = 76% (95% CI 5% to 94%; p-value = 0.042).Stepwise selection (P>0.05 for removal), candidate variables vaccination status plus variables significant (P≤0.05) in univariate analysis; dog meat or raw vegetables, and not drinking bottled or boiled water most of the time.