Neonatal rotavirus vaccination with RIT 4237 bovine rotavirus vaccine: a preliminary report.

We vaccinated 244 newborn infants orally with RIT 4237 bovine rotavirus vaccine or placebo and followed them serologically and clinically for 16 months. Initially 39 of the 119 (33%) vaccine recipients compared with 1 of the 120 placebo recipients seroconverted by enzyme-linked immunosorbent assay-immunoglobulin M. After the first winter rotavirus season, at 7 months of age 55% of the vaccinated infants and 37% of the unvaccinated infants were rotavirus-seropositive by enzyme-linked immunosorbent assay-immunoglobulin G (P less than 0.01, chi square test). At 12 months of age, after a low rotavirus prevalence season, 34% of the vaccinated children and 23% of the unvaccinated children remained seropositive. There were 14 confirmed episodes of rotavirus gastroenteritis in the vaccine group and 10 episodes in the placebo group during the first 16 months. However, only 1 of the episodes in the vaccine group was severe, 4 were moderately severe and 9 were mild, whereas 7 episodes in the placebo group were severe and 3 were moderately severe (P less than 0.001 between groups, Fisher's exact test). There was no clear correlation between vaccine-induced clinical protection and initial serologic response (enzyme-linked immunosorbent assay-immunoglobulin M) to vaccination, but during follow-up severe rotavirus gastroenteritis was more likely to occur in children with no serum rotavirus immunoglobulin G antibody at the time of infection. We conclude at the present stage that neonatal rotavirus vaccination with RIT 4237 vaccine gives no protection against rotavirus infection but appears to modify the severity of gastroenteritis.