Effectiveness of rotavirus vaccine against hospital admission for rotavirus diarrhoea in Brazilian children: a case-control study

Abstract

BackgroundIn Brazil, before the introduction of the monovalent rotavirus vaccine in 2006, between 22% and 38% of children younger than age 5 years admitted to hospital with diarrhoea had positive stool samples for rotavirus. Rotavirus vaccine effectiveness against hospital admission caused by the G2[P4] genotype in Brazil is estimated to be 40–85%. We estimated overall and genotype-specific vaccine effectiveness and the effect of time since vaccination on hospital admission for Brazilian children with rotavirus diarrhoea. MethodsWe did a case-control study of ten general hospitals from the Rotavirus Diarrhoea Surveillance System of five regions of Brazil, from July 2008, to August 2011. 215 patients (aged 4–24 months) with confirmed rotavirus diarrhoea were recruited and 1961 controls (admitted to hospital without diarrhoea) were frequency matched to cases by sex and age group. We estimated vaccine effectiveness with multivariable logistic regression adjusted for year of birth; sex and age; variance estimation of Jackknife (crude) and confounders (adjusted). FindingsTwo-dose crude vaccine effectiveness was 76% (95% CI 58–86), lasting for 2 years. Two-dose adjusted effectiveness was 72% (44–85), suggesting no noticeable confounding. 80 (51%) patients had genotype G2[P4] and 24 (15%) had G1[P8]. Two-dose vaccine effectiveness was 89% (78–95) for G1[P8] and 76% (64–84) for G2[P4]; 74% (35–90) for all G1, 76% (63–84) for all G2, and 63% (27–99) for all non-G1 or non-G2. One dose vaccine effectiveness for all genotypes was 62% (39–97). InterpretationTwo-dose vaccine effectiveness for prevention of hospital admission with rotavirus diarrhoea was high, lasted for at least 2 years, and was similar for both G1[P8] and G2[P4]. On the basis of these findings we recommend the continued use of this vaccine in the Brazilian Immunization Program and monitoring of the emergence of unusual and novel rotavirus genotypes. FundingHealth Surveillance of the Ministry of Health of Brazil.