Two oral doses of the live attenuated G1P[8] HRV vaccine were highly efficacious in protecting infants against severe rotavirus gastroenteritis, significantly reduced the rate of severe gastroenteritis from any cause, and were not associated with an increased risk of intussusception. (ClinicalTrials.gov numbers, NCT00139347 and NCT00263666.)

No abstract

In this study in a developing country, the quadrivalent rhesus rotavirus-based vaccine induced a high level of protection against severe diarrheal illness caused by rotavirus.

The most extensively explored strategy for rotavirus vaccination has been the Jennerian approach, which uses an antigenically related rotavirus strain from an animal host as the immunogen to induce protection against the 4 epidemiologically important group A rotavirus VP7 serotypes. Because this approach has shown limited efficacy, a modified Jennerian approach was developed with the goal of achieving broader antigenic coverage. Four VP7 serotypes were incorporated into a quadrivalent vaccine comprised of three rhesus-human rotavirus reassortants, each with 10 rhesus rotavirus genes and 1 human rotavirus gene that encodes VP7 serotype 1, 2, or 4 specificity; the rhesus rotavirus itself provides coverage for VP7 serotype 3. This approach appears quite promising for preventing severe rotavirus diarrhea, including those episodes that lead to dehydration. Additional strategies under development stress the role not only of human rotavirus VP7 but also of human rotavirus VP4, the other outer capsid protein that also induces neutralizing antibodies.

The need for safe and effective vaccines to reduce morbidity and mortality caused by rotavirus gastroenteritis in children is well-known. A live attenuated monovalent rotavirus vaccine (Rotarix) containing human rotavirus strain RIX4414 of G1P1A P[8] specificity is being developed to meet the global need. An overview of RIX4414 trials in developed and developing settings is presented for 3 selected trials conducted in Finland (pilot study), Latin America (Brazil, Mexico and Venezuela) and Singapore involving 5024 infants. The vaccine was well-tolerated, with no increase in any solicited symptoms as compared with the placebo. After 2 doses, 61-91% of vaccinated infants developed rotavirus-specific IgA antibodies. There was no interference with immunogenicity of coadministered routine pediatric vaccines. Rotarix significantly reduced rotavirus gastroenteritis episodes and rotavirus-related hospitalizations in vaccinated infants compared with placebo recipients (P < 0.05). Vaccine efficacy was observed against severe rotavirus gastroenteritis caused by G1 and non-G1 types including the emerging G9 type (P < 0.05) in Latin America. These results show prospects for widespread use of Rotarix to reduce rotavirus disease burden and warrant continued worldwide evaluation.