Reduction in severity of all-cause gastroenteritis requiring hospitalisation in children vaccinated against rotavirus in Malawi

Abstract

AbstractBackgroundRotavirus is the major cause of severe gastroenteritis in children aged <5 years. Introduction of Rotarix® rotavirus vaccine (RV1) in Malawi in 2012 has reduced rotavirus-associated hospitalisations and diarrhoeal mortality. However, RV1 impact on gastroenteritis severity remains unknown. We conducted a hospital-based surveillance study to assess RV1 impact on gastroenteritis severity in children aged <5 years, in Malawi.MethodsStool samples were collected from children hospitalised with acute gastroenteritis from December 2011 – October 2019. Gastroenteritis severity was determined using Ruuska and Vesikari scores. Rotavirus was detected in stool using Enzyme Immunoassay. Rotavirus genotypes were determined using nested RT-PCR. Associations between RV1 vaccination and gastroenteritis severity were investigated using adjusted linear regression.ResultsIn total, 3,159 children were recruited. After adjusting for Mid-Upper Arm Circumference, age, weight, gender and receipt of other vaccines, all-cause gastroenteritis severity scores were 2.21 units lower (95% CI 1.85, 2.56; p<0.001) among RV1-vaccinated (n=2,224) compared to RV1-unvaccinated children (n=935); the decrease was comparable between rotavirus-positive and rotavirus-negative cases in all age groups. The reduction in severity score was observed against every rotavirus genotype, although the magnitude was smaller among those infected with G12P[6] compared to the remaining genotypes (p=0.011). Other than RV1 vaccination, age was the only variable associated with gastroenteritis severity. Each one-year increment in age was associated with a decrease of 0.43 severity score (95% CI 0.26, 0.60; p<0.001).ConclusionOur findings provide additional evidence of RV1 impact in a high disease burden, low-income country, lending further support to Malawi’s rotavirus vaccine programme.SummaryIn a long-term hospital-based surveillance study in Malawi, we found evidence of the reduction in gastroenteritis severity among hospitalised RV1-vaccinated children infected with both homotypic and heterotypic rotavirus strains and off-target RV1 vaccine effects against non-rotavirus diarrhoeal severity.