Effect of rotavirus genetic diversity on vaccine impact.

Group A rotaviruses (RVAs) are the leading cause of gastroenteritis, causing 0.2 million deaths and several million hospitalisations globally each year. Four rotavirus vaccines (RotarixTM , RotaTeqTM , Rotavac® and ROTASIIL® ) have been pre-qualified by the World Health Organization (WHO), but the two newly pre-qualified vaccines (Rotavac® and ROTASIIL® ) are currently only in use in Palestine and India, respectively. In 2009, WHO strongly proposed that rotavirus vaccines be included in the routine vaccination schedule of all countries around the world. By the end of 2019, a total of 108 countries had administered rotavirus vaccines, and 10 countries have currently been approved by Gavi for the introduction of rotavirus vaccine in the near future. With 39% of global coverage, rotavirus vaccines have had a substantial effect on diarrhoeal morbidity and mortality in different geographical areas, although efficacy appears to be higher in high income settings. Due to the segmented RNA genome, the pattern of RVA genotypes in the human population is evolving through interspecies transmission and/or reassortment events for which the vaccine might be less effective in the future. However, despite the relative increase in some particular genotypes after rotavirus vaccine use, the overall efficacy of rotavirus mass vaccination worldwide has not been affected. Some of the challenges to improve the effect of current rotavirus vaccines can be solved in the future by new rotavirus vaccines and by vaccines currently in progress.