Review of rotavirus vaccine trials in Finland.

Oral rotavirus vaccines, including bovine rotavirus strains RIT 4237 and RIT 4256, rhesus rotavirus (RRV) vaccine, rhesus-human rotavirus vaccine reassortants (D x RRV, DS-1 x RRV, and tetravalent RRV), and human nursery rotavirus strain M37, have been evaluated in 5353 Finnish infants for safety, immunogenicity, and efficacy against rotavirus gastroenteritis. Bovine rotavirus vaccines were nonreactogenic in infants, whereas RRV-based and M37 vaccines were occasionally associated with febrile reactions 2-5 days after vaccination. All vaccines showed dose-dependent immunogenicity. Vaccine efficacy correlated with overall immunogenicity but not with the vaccine virus G serotype. For each vaccine, protective efficacy was better against severe rotavirus disease than against any rotavirus-associated gastroenteritis. Maximal protective efficacy against any rotavirus gastroenteritis in subjects with demonstrable vaccine immunogenicity was approximately 75%. To achieve similar protection in all vaccinees, efforts should be focused on enhancing the immunogenicity of oral rotavirus vaccines.