Impact of rotavirus vaccination on rotavirus hospitalisationrates among a resource-limited rural population in Mbita,Western Kenya

Abstract

A two-dose oral monovalent rotavirus vaccine (RV1) was introduced into the KenyanNational Immunization Program in July 2014. We assessed trends in hospitalisation for rotavirus-specific acute gastroenteritis (AGE) and strain distribution among children <5 years in a rural,resource-limited setting in Kenya before and after the nationwide implementation of the vaccine.methods Data on rotavirus AGE and strain distribution were derived from a 5-year hospital-basedsurveillance. We compared rotavirus-related hospitalisations and strain distribution in the 2-yearpost-vaccine period with the 3-year pre-vaccine baseline. Vaccine administrative data from the Unitof Vaccines and Immunization Services (UVIS) for Mbita sub-county were used to estimate rotavirusimmunisation coverage in the study area.results We observed a 48% (95% CI: 27–64%) overall decline in rotavirus-related hospitalisationsamong children aged <5 years in the post-vaccine period. Coverage with the last dose of rotavirusvaccine increased from 51% in year 1% to 72% in year 2 of the vaccine implementation.Concurrently, reductions in rotavirus hospitalisations increased from 40% in the first year to 53% inthe second year of vaccine use. The reductions were most pronounced among the vaccine-eligiblegroup, with the proportion of cases in this age group dropping to 14% in post-vaccine years from ahigh of 51% in the pre-vaccine period. A diversity of rotavirus strains circulated before theintroduction of the vaccine with G1P[8] being the most dominant strain. G2P[4] replaced G1P[8] asthe dominant strain after the vaccine was introduced.conclusions Rotavirus vaccination has resulted in a notable decline in hospital admissions forrotavirus infections in a rural resource-limited population in Kenya. This provides early evidence forcontinued use of rotavirus vaccines in routine childhood immunisations in Kenya. Our data alsounderscore the need for expanding coverage on second dose so as to maximise the impact of the vaccine.