Impact and effectiveness of monovalent rotavirus vaccine in Tajik children.

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.

Rotavirus hospitalizations among children <5 years of age-Tajikistan, 2013-2014.

BACKGROUND: In January 2015, Tajikistan introduced the monovalent rotavirus vaccine into the national immunization program. Our objective was to estimate pre-vaccine burden of rotavirus-associated hospitalizations in children <5 years of age in Tajikistan. METHODS: During January 2013-December 2014, active surveillance for acute gastroenteritis (AGE)-associated hospitalizations in children <5 years of age was conducted by sentinel surveillance site staff. Patients' demographic and clinical data were summarized and a stool sample was collected. An Enzyme Linked Immunosorbent Assay was used for diagnosis of rotavirus infection and subset of the specimens was sent for polymerase chain reaction (PCR) genotyping. RESULTS: Of 2860 eligible children enrolled and tested, 1207 (42%) were positive for rotavirus. An increase in the number and proportion of rotavirus cases attributed to rotavirus season, with positivity rates >40%, was annually observed during June-September. The median age of rotavirus patients was 9 months and 939/1207 (78%) rotavirus patients were aged 6-23 months. Most (1097/1203; 91%) rotavirus patients were treated with intravenous fluids. G1P[8] was the predominant genotype during both years of surveillance, accounting for 133/222 (60%) of genotyped cases. CONCLUSION: Rotavirus is a major cause of hospitalization due to severe AGE in children <5 years of age in Tajikistan, accounting for >40% of cases. Continued, enhanced rotavirus surveillance may allow documentation of changes in rotavirus disease burden following vaccine introduction and assessment of vaccine effectiveness.