Rotavirus group A genotype circulation patterns across Kenya before and after nationwide vaccine introduction, 2010-2018.
Mwanga MJ., Owor BE., Ochieng JB., Ngama MH., Ogwel B., Onyango C., Juma J., Njeru R., Gicheru E., Otieno GP., Khagayi S., Agoti CN., Bigogo GM., Omore R., Addo OY., Mapaseka S., Tate JE., Parashar UD., Hunsperger E., Verani JR., Breiman RF., Nokes DJ.
BackgroundKenya introduced the monovalent G1P [8] Rotarix® vaccine into the infant immunization schedule in July 2014. We examined trends in rotavirus group A (RVA) genotype distribution pre- (January 2010-June 2014) and post- (July 2014-December 2018) RVA vaccine introduction.MethodsStool samples were collected from children aged ResultsWe genotyped 614 samples in pre-vaccine and 261 in post-vaccine introduction periods. During the pre-vaccine introduction period, the most frequent RVA genotypes were G1P [8] (45.8%), G8P [4] (15.8%), G9P [8] (13.2%), G2P [4] (7.0%) and G3P [6] (3.1%). In the post-vaccine introduction period, the most frequent genotypes were G1P [8] (52.1%), G2P [4] (20.7%) and G3P [8] (16.1%). Predominant genotypes varied by year and site in both pre and post-vaccine periods. Temporal genotype patterns showed an increase in prevalence of vaccine heterotypic genotypes, such as the commonly DS-1-like G2P [4] (7.0 to 20.7%, P ConclusionGenotype prevalence varied from before to after vaccine introduction. Such observations emphasize the need for long-term surveillance to monitor vaccine impact. These changes may represent natural secular variation or possible immuno-epidemiological changes arising from the introduction of the vaccine. Full genome sequencing could provide insights into post-vaccine evolutionary pressures and antigenic diversity.