Two doses of the live attenuated G1P human rotavirus (HRV) vaccine are highly efficacious in protecting infants against severe rotavirus gastroenteritis, a phase-3 trial of the vaccine has shown. The vaccine also significantly reduced the rate of severe gastroenteritis from any cause and was not associated with increased risk of intussusception. The trial, in healthy 6- to 13-week-old Latin-American and Finnish infants, comprised 63,000 infants who were studied for vaccine safety; of this group, 20,000 also were evaluated for vaccine efficacy. Infants received the first oral dose of HRV vaccine or placebo at approximately 2 months of age; the second dose, at approximately 4 months. The two groups were followed for a median of 100 days from the first dose to assess adverse events (safety surveillance period) and for nine to 10 months to assess efficacy.
Nine vaccine recipients and 16 placebo recipients developed intussusception during the safety surveillance period. Of those 25 infants, 10 developed intussusception after the first dose; 15, after the second dose. Neither dose was associated with any temporal cluster of intussusception cases. Furthermore, infants in the vaccine group experienced fewer serious adverse events than those in the placebo group and were hospitalized less often. Overall mortality was similar in both groups.
Vaccine efficacy against HRV gastroenteritis was 84.7% from two weeks after the second dose until 1 year of age, with 12 children in the vaccine group and 77 in the placebo group developing severe HRV gastroenteritis. Efficacy increased with disease severity, reaching 100% against more severe HRV gastroenteritis. Vaccination also resulted in a 40% reduction in severe gastroenteritis (requiring rehydration) from any cause and a 42% reduction in hospitalization for diarrhea from any cause (Ruix-Palacios GM et al: N Engl J Med 2006;354:11).
Availability of these new vaccines is good news for children everywhere. Worldwide, rotavirus causes almost 1.5 million deaths annually and is responsible for as many as one third of hospitalizations for diarrhea.