Molecular Epidemiology of Rotavirus among Children in Western Canada: Dynamic Changes in Genotype Prevalence in Four Consecutive Seasons

Rotavirus molecular surveillance remains important in the post vaccine era in order to monitor the changes in transmission patterns, identify vaccine induced antigenic changes and discover potentially pathogenic vaccine related strains. The Canadian province of Alberta introduced rotavirus vaccination into its provincial vaccination schedule June 2015. To evaluate the impact of this program on stool rotavirus positivity rate, strain diversity and seasonal trends, we analyzed a prospective cohort of children with acute gastroenteritis recruited between December 2014 and August 2018. We identified dynamic changes in rotavirus positivity and genotype trends during pre- and post- rotavirus vaccine introduction periods. Genotypes G9P[8], G1P[8], G2P[4] and G12P[8] predominated consecutively each season with overall lower rotavirus incidence rates in 2016 and 2017. The demographic and clinical features of rotavirus gastroenteritis were comparable among wild type rotaviruses; however, children with G12P[8] infections were older (P<0.001). Continued efforts to monitor changes in the molecular epidemiology of rotavirus using whole genome sequence characterization is needed to further understand the impact of the selection pressure of vaccination on rotavirus evolution.