EFFICACY AND SAFETY OF HIGH-DOSE RHESUS-HUMAN REASSORTANT ROTAVIRUS VACCINE IN NATIVE-AMERICAN POPULATIONS

Objectives: We compared the efficacy, safety and immunogenicity of a r hesus rotavirus tetravalent vaccine (RRV-TV), a rhesus rotavirus monov alent (serotype 1) vaccine (RRV-S1), and placebo in healthy American I ndian infants for two rotavirus seasons. Study design: Infants aged 6 to 24 weeks were enrolled in a randomized, double-blind efficacy study . Infants were orally administered RRV-TV (4 x 10(5) plaque-forming un its per dose), RRV-S1 (4 x 10(5) plaque-forming units per dose), or pl acebo at 2, 4, and 6 months of age. Stools collected during episodes o f gastroenteritis were tested for detection of rotavirus antigen. A to tal of 1185 infants received at least one dose of a study vaccine or p lacebo, and 1051 received all three doses according to the protocol. R esults: During the first year of surveillance, the estimates of vaccin e efficacy (with 95% confidence interval) for preventing rotaviral gas troenteritis were 50% (26, 67) for RRV-TV and 29% (-1, 50) for RRV-S1. In this population only 6% of rotaviral gastroenteritis episodes amon g placebo recipients were associated with type G1 disease. For severe disease the estimates of vaccine efficacy were higher: 69% (29, 88) fo r RRV-TV and 48% (-4, 75) for RRV-S1. Conclusions: These data indicate that RRV-TV is moderately efficacious in preventing all episodes of g astroenteritis caused by rotavirus and is most efficacious against the severe disease characteristic of rotaviral illness.