Risk factors for hospital admission of Brazilian children with non-rotavirus diarrhoea: a case control-study.

BACKGROUND: Rotavirus has been the leading cause of severe cases of acute diarrhoea (AD) among children worldwide; however, in the same areas, a large reduction in AD related to rotavirus has been observed after the introduction of the rotavirus vaccine. In Brazil, where there is a high rotavirus vaccine coverage, AD caused by pathogens other than rotavirus is still a frequent cause of outpatient visits and hospitalisations among children under 5 years. METHODS: A hospital-based case-control study enrolled children aged 4 to 24 months admitted to 10 hospitals from all five Brazilian Regions. Cases (n=1178) were children admitted with diarrhoea who tested negative for rotavirus in a stool sample. Controls (n=2515) were children admitted without diarrhoea, frequency matched to cases by sex and age group. We estimated odds ratios using logistic regression, in a hierarchical approach according to a previously defined conceptual framework. Population-attributable fractions (PAF) were estimated for each variable, each block and for all significant variables in the latter model adjusted. RESULTS: The factors studied accounted for 41% of the non-rotavirus AD hospital admissions and the main risk factors included lack of adequate excreta disposal (PAF=12%), untreated drinking water (PAF=11%) and a history of previous hospitalization due to AD (PAF=21%). Low socio-economic conditions, no public water supply, crowding and low weight-for-age made smaller contributions. CONCLUSIONS: These findings further our knowledge of risk factors associated with severe AD in the post-rotavirus vaccination era. We recommend further increase in coverage of basic sanitation, improvements in water quality and further expansion of primary healthcare coverage to reduce the occurrence of non-rotavirus severe diarrhoea and subsequent hospitalization of Brazilian children.

Effectiveness of rotavirus vaccine against hospitalized rotavirus diarrhea: A case-control study.

Rotavirus is one of the leading cause of hospitalization and outpatients visits among children under five years. This study evaluated overall and genotype-specific vaccine effectiveness of oral monovalent rotavirus vaccine (G1P[8] strain) in preventing hospital admission of Brazilian children with rotavirus acute diarrhea. A hospital based case-control study was conducted in five Regions of Brazil using the National Rotavirus Acute Diarrhea Surveillance System from July 2008 to August 2011. A total of 215 cases (aged 4-24 months) admitted with confirmed rotavirus diarrhea were recruited and 1961 controls hospitalized without diarrhea were frequency matched by sex and age group to cases. Two-dose adjusted vaccine effectiveness (adjusted by year of birth and the frequency matching variables) was 76% (95%CI: 58-86) lasting for two years. Effectiveness controlled by the available potential confounders was 72% (95%CI: 44-85), suggesting no appreciable confounding by those factors for which adjustment was made. In a half of the cases the rotavirus genotype was G2P[4] and in 15% G1P[8]. Genotype-specific VE (two doses) was 89% (95%CI: 78-95), for G1P[8] and 76% (95%CI: 64-84) for G2P[4]. For all G1, it was 74% (95%CI: 35-90), for all G2, 76% (95%CI: 63-84), and for all non G1/G2 genotypes, 63% (95%CI: -27-99). Effectiveness for one dose was 62% (95%CI: 39-97). Effectiveness of two-dose monovalent rotavirus vaccine in preventing hospital admission with rotavirus diarrhea was high, lasted for two years and it was similar against both G1P[8] and G2P[4]. Based on the findings of the study we recommend the continued use of rotavirus in the Brazilian National Immunization Program and the monitoring of the early emergence of unusual and novel rotavirus genotypes.