Effectiveness of Human Rotavirus Vaccine, Rotarix™ Against Rotavirus Severe Gastroenteritis (RV SGE) in Infants

Inclusion Criteria: Inclusion criteria for surveillance subjects * A male or female child aged \< 60 months at the time of admission (a child becomes ineligible on the day of its fifth birthday). * Subject admitted with acute GE as an inpatient to the study site during the study period. * Written informed consent obtained from the parent or guardian of the subject. Selection criteria for cases Cases will be limited to those surveillance subjects: * who are born after 1 November 2005 (date of availability of Rotarix™ vaccination in Singapore), * who are aged at least 16 weeks at the time of hospital admission. * whose stool samples are tested positive for RV. Selection criteria for controls All controls must satisfy the following criteria at study entry: * Admitted for acute disease with non-GE causes in the same hospital as the case , with the closest admission date to the cases. * Aged at least 16 weeks at the time of hospital admission. * Born within a range of ± 2 weeks from the date of birth of cases. In case there is no suitable match, then the range would be extended to ± 4 weeks. * Written informed consent obtained from the subject's parents/guardians. Exclusion Criteria: For enrolment of surveillance subjects The following criteria should be checked at the time of study entry. If any apply, the subject must not be included in the study: * The diagnoses at admission to the study site do not include acute GE. * Children for whom stool samples are not available up to 48 hours after admission. * The onset of GE is after 48 hours of admission to the hospital (i.e. nosocomial GE). * Children with a history of chronic and genetic diseases. For selection of cases In addition to the exclusion criteria for surveillance subjects, cases will not be selected if the following criterion applies: * Subjects who had a previous episode of acute GE less than a week back i.e. recurrent GE episode. * Subjects who have been already enrolled in the study. * Subjects whose vaccination history could not be ascertained. For selection of controls The following criteria should be checked at the time of study entry. If any apply, the controls must not be included in the study: * Child who has symptoms of GE on the day of interview of his/her parent or guardian or had an episode of GE within 14 days prior to the day of interview. * Child who has been already enrolled in the study as case or control. * The onset of GE occurs after admission at the hospital. * Child whose vaccination history could not be ascertained.