Abstract:
Objectives: A two-dose oral monovalent rotavirus vaccine (RV1) was introduced into the
Kenyan National 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-based surveillance. We compared rotavirus-related hospitalisations and strain
distribution in the 2-year post-vaccine period with the 3-year pre-vaccine baseline.
Vaccine administrative data from the Unit of Vaccines and Immunization Services
(UVIS) for Mbita sub-county were used to estimate rotavirus immunisation coverage in
the study area.
Results: We observed a 48% (95% CI: 27-64%) overall decline in rotavirus-related
hospitalisations among children aged <5 years in the post-vaccine period. Coverage with
the last dose of rotavirus vaccine 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% in the second year of vaccine use. The reductions were
most pronounced among the vaccine-eligible group, with the proportion of cases in this
age group dropping to 14% in post-vaccine years from a high of 51% in the pre-vaccine
period. A diversity of rotavirus strains circulated before the introduction of the vaccine
with G1P[8] being the most dominant strain. G2P[4] replaced G1P[8] as the dominant
strain after the vaccine was introduced.
Conclusions: Rotavirus vaccination has resulted in a notable decline in hospital
admissions for rotavirus infections in a rural resource-limited population in Kenya. This
provides early evidence for continued use of rotavirus vaccines in routine childhood
immunisations in Kenya. Our data also underscore the need for expanding coverage on
second dose so as to maximise the impact of the vaccine.