Field trial of rhesus rotavirus vaccine in infants.

Orally administered rhesus rotavirus vaccine (RRV) was evaluated in a placebo-controlled study in 176 infants (ages 2 to 4 months). Eighty-eight infants received a dose of 10(4) plaque-forming units of the vaccine, and 88 received the placebo. RRV was well-tolerated but mildly reactogenic in the 10 days after vaccination. There were mild febrile reactions (greater than or equal to 38 degrees C rectally) in 40% of the vaccinees and in 16% of the placebo recipients (P = 0.001). More of the vaccinees had loose stools than did the placebo recipients (P less than 0.05). RRV was immunogenic and induced a 4-fold or greater rise in serum neutralizing antibody responses in 67% of the vaccinees; however, breast-fed infants were less likely to develop a seroresponse than infants who were not breast-fed. Despite the good immunogenicity of RRV the overall incidence of rotavirus-associated illnesses was similar between the vaccine and placebo recipients. The failure of RRV in Rochester may be related to the fact that the circulating rotaviruses were predominantly serotype 1 and RRV is a serotype 3 rotavirus. Because the serotypes of rotavirus that predominate may vary from year to year, a polyvalent preparation may be necessary to provide effective vaccination against rotaviruses.