The main aim of this study is to investigate cases of rotavirus gastroenteritis in Belgian children with opportunity to receive Rotarix™ to monitor the potential occurrence of genetic drifts (point mutations) in the vaccine strain and the occurrence of genetic shifts (re-assortments) between vaccine and naturally circulating wild-type strains in Belgium population after the introduction of Rotarix™. The study will also detect if there is any alteration in rotavirus pathogenicity conferred by re-assortment and if the mutated vaccine strain is still efficacious in preventing rotavirus gastroenteritis.

This study is conducted in two phases: Phase I and Phase II. Phase I will be retrospective and consist of re-using the data collected in RotaBel (EPI-ROTA-111426) study. Phase II will be prospective and consist of maintaining the active surveillance system to identify rotavirus cases in several hospitals in Belgium.

Inclusion Criteria:

Phase I:

• Vaccinated and unvaccinated confirmed G1 and/or P[8] rotavirus gastroenteritis cases from the RotaBel study.

Phase II:

• A male or a female, born after 1 October 2006 and aged between 14 weeks and < 5 years at the time of hospital admission.
• Child admitted at the study hospital for severe gastroenteritis during the study period.
• Onset of severe gastroenteritis ≤14 days prior to admission.
• Child whose stool sample was tested positive for rotavirus by a hospital routine test.
• Written informed consent obtained from the parent or guardian of the child.

Exclusion Criteria:

• Child in care.

Children confirmed with G1 and/or P[8] cases from the RotaBel study, children between 14 weeks and <5 years of age, hospitalized for severe gastroenteritis in the study hospitals and who are tested positive for rotavirus