Results from a double-blind, placebo-controlled trial demonstrated that two doses of the rotavirus vaccine candidate given two months apart at two and four months of age, gave 85 percent protection against severe rotavirus disease and 100 percent protection against more severe disease. This protection was proven against the most common circulating strains: G1P, G3P, G4P and the globally emerging G9P strain. A meta-analysis considering data from this trial and other efficacy studies conducted with similar methods showed 67 percent protection against G2P rotavirus disease.
The safety analysis revealed a lower incidence of serious adverse events in children receiving the rotavirus vaccine candidate compared to children receiving placebo. This finding was attributable to the lower number of gastrointestinal disease related serious adverse events in those receiving the rotavirus vaccine candidate. In addition, the safety analysis looked for, but did not find, any evidence of an increased risk for intussusception in recipients of the vaccine candidate compared to placebo. Intussusception is a complication which was observed with a previously marketed rotavirus vaccine (see editor's note). In previous studies, the most common adverse events were reported with similar frequency in both study arms; they included irritability and loss of appetite, fever, fatigue, diarrhea, vomiting, flatulence, abdominal pain and regurgitation of food.
Lead investigator Guillermo M. Ruiz-Palacios, MD, Instituto Nacional de Ciencas Medicas y Nutricion, Mexico City, Mexico commented on the data: "Rotavirus is highly contagious and infects virtually every child worldwide by the age of three years. It is the cause of a third of all hospitalizations due to gastroenteritis and is associated with a high mortality due to diarrhea in developing countries. This vaccine has been shown to be highly effective in combating this disease - it should be considered for inclusion in the routine vaccination schedules in healthcare systems around the world."
A total of 63,225 infants from 12 countries were enrolled in the study. Infants were randomly assigned to receive two oral doses of either the rotavirus vaccine candidate or placebo. From administration of the first dose until one to three months after administration of the second dose, the entire study population was followed for the assessment of intussusception and serious adverse events. In addition, a subgroup of 20,169 was followed up to one year of age for the assessment of efficacy.
Beatrice De Vos, Director Worldwide Medical Affairs, GlaxoSmithKline Biologicals, commented: "Rotavirus is highly contagious regardless of sanitary conditions. Rotavirus can be detected in about one-third of all children hospitalized for diarrhea worldwide and mortality remains highest in the developing world. The now published data give confidence that vaccination at an early age has the potential to provide protection prior to the peak incidence of rotavirus (at 6-24 months of age)."
About GSK's Rotavirus Vaccine Candidate
GSK's rotavirus vaccine candidate has been developed by GlaxoSmithKline Biologicals since 1997. The strain RIX4414 derives from the strain 89-12 which was originally developed by Richard Ward, MD, at the Children's Hospital of Cincinnati, and which was in-licensed from AVANT Immunotherapeutics. It is the first attenuated human rotavirus oral vaccine conferring protection against severe rotavirus diarrhea with data that suggest efficacy against emergent strains. Data demonstrates that the vaccine is highly immunogenic and can be co-administered with all major infant vaccinations including oral polio vaccine.
Since its launch in Mexico in 2005, the rotavirus vaccine candidate has been licensed in several additional countries worldwide (12 Latin American countries including Brazil; Philippines and Singapore being the first Asian countries). The vaccine received a positive opinion from the Committee for Medicinal Products for Human Use (CHMP), the Scientific Committee which evaluates the quality, safety and efficacy of medicinal products in the European Union on December 15, 2005. According to the new legislation, a European Marketing Authorization from the European Commission could be expected from late February 2006 onwards which, if granted, would make this vaccine the first rotavirus vaccine available to children in Europe. Furthermore, marketing applications have been filed in 75 countries. The vaccine candidate is not approved in the US, however GSK plans to file a Biologics License Application in the US and discussions are ongoing with the US Food and Drug Administration.
Recently, Brazil and Panama included for the first time the rotavirus vaccine in their national official vaccination calendars. As part of the government's pediatric immunization program, vaccination with GSK's rotavirus vaccine will be available free at public health clinics in Brazil and Panama.
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Notes to editors
Intussusception is the most common abdominal emergency in children younger than one year of age, and occurs when one portion of the intestines slides into the next, like pieces of a telescope. It is now required to perform analysis of data from oral infant rotavirus vaccine trials to assess any potential risk of increased intussusception.