Impact and effectiveness of monovalent rotavirus vaccine in Tajik children.

ABSTRACT

BACKGROUND: In 2015, Tajikistan became the second country in Central Asia to introduce rotavirus vaccine into its national immunization program. Before vaccine introduction, rotavirus was estimated to cause > 40% of pediatric diarrhea hospitalizations in Tajikistan. We aimed to assess the impact of rotavirus vaccine introduction on rotavirus disease burden and estimate rotavirus vaccine effectiveness (VE). METHODS: Using surveillance data from 2013 through 2019, we examined trends in monthly hospital admissions among children < 5 years old, before and after rotavirus vaccine introduction. Poisson regression was used to quantify decreases. VE was estimated using a test-negative case control design, with data from admissions during 2017 - 2019. Immunization records were obtained from clinics. RESULTS: Among enrolled children, rotavirus positivity declined from 42% to 25% in the post-vaccine introduction period, a decrease of 41% (95% Confidence Interval [CI] 36 - 45%). Declines were greatest in children < 12 months of age. Estimated VE of a complete course of rotavirus vaccine was 55% (95% CI 21 - 73%) among children 5 - 59 months of age and 64% (95% CI 36 - 80%) among children 5 - 23 months of age. VE point estimates were higher among children receiving both doses of rotavirus vaccine non-concurrently with OPV and among children receiving their first dose of rotavirus vaccine at 4 - 11 months of age, but CIs were wide and overlapping. CONCLUSIONS: Our data demonstrate that rotavirus vaccine introduction was associated with a substantial reduction in pediatric rotavirus hospitalization burden in Tajikistan, and that rotavirus vaccination is effective in Tajik children.