Paediatric rotavirus gastroenteritis: A prospective study of regional prevalent genotypes, genotype correlation with disease severity and viral co-infection in County Mayo, Ireland, in the year following rotavirus vaccine introduction in Ireland.

Rotavirus A (RV) is the primary cause of gastroenteritis in children worldwide and a leading cause of gastroenteritis in children younger than three years, with a significant burden both globally and in Ireland. Rotavirus vaccine (Rotarix™) was introduced into Ireland in 2016. The aim of this study was to determine the diversity and frequency of, and predominant, RV genotypes, nosocomial acquisition, viral co-infections and severity of RV infection in Ireland in the post-vaccination year, from November 18th 2016 to November 18th 2017. The study included all children up to 3 years of age who had presented to Mayo University Hospital or were admitted with vomiting and diarrhoea, and had their stool tested for rotavirus and other viruses by real-time PCR in the National Virus Reference Laboratory. The Vesikari Scoring System was used to assess disease severity. The results showed that rotavirus was a leading cause of gastroenteritis (37 patients, 24.6 % of a total of 150 patients) and gastroenteritis-related hospitalisation (27 patients were admitted, 21 % of a total of 128 patients). Severe rotaviral gastroenteritis was noted in 78 % of all RV gastroenteritis (37 patients). The RV strain G1P[8], including the vaccine G1P[8] strain (Rotarix™), was the most predominant genotype (47 %), followed by G2P[4] (31 %), G4P[8] (8%), G12P[8] (8%) and G9P[8] (6%). RV co-infection with other viruses was detected in four cases (11 %), of whom three cases (75 %) were severe. Rotarix™ was detected in six vaccinated patients (35 %), 50 % were mild disease. Nosocomial infection was detected in one case. These results indicated that RV remained the leading cause of paediatric gastroenteritis during the post vaccination year in Ireland.