Background: Group A rotavirus (RVA) gastroenteritis is an important cause of childhood morbidity and mortality worldwide. Safe and effective RVA vaccines are considered to be a high-impact and cost-effective public health intervention tool to greatly reduce the burden of rotavirus disease. RVA virion is composed of three layers enclosing a genome of 11 segments of double-stranded RNA. The two outer capsid proteins, VP7 and VP4 define the G and P genotypes, respectively. Pre-vaccine introduction data on RVA disease burden and genotype features is critical to support an informed and evidence-based decision about necessity of introducing rotavirus vaccines into a country and to provide baseline data for monitoring the impact of the introduced vaccines. In July 2014, Kenya introduced rotavirus vaccine into her national immunization program. This national rollout of rotavirus vaccine provided an opportunity to assess the real-world impact of rotavirus vaccination on rotavirus disease epidemiology and strain distribution in the country. Thus, in the course of my PhD program, I endeavored to determine the disease epidemiology and molecular characteristics of RVA strains among children aged <5 years in Central Kenya before and after the introduction of rotavirus vaccine. Furthermore, since immunization coverage will have an influence on the overall impact of rotavirus vaccination in the country, I estimated the rotavirus immunization coverage in a subcounty within my study area.