Because the bowel obstruction was so rare, and the increased incidence was so small, the only way to evaluate the safety of a new rotavirus vaccine was to launch a clinical trial involving more than 60,000 infants.
In 2000, Merck asked Matson to serve as the U.S. principal investigator in a clinical trial of RotaTeq, a vaccine under development.
RotaTeq targets five major strains of rotavirus, which account for 90 percent of rotavirus disease. The trial involved infants in the United States, Belgium, Costa Rica, Finland, Germany, Guatemala, Italy, Jamaica, Mexico, Sweden and Taiwan.
Infants were randomly assigned to receive three doses of vaccine or placebo, given four to 10 weeks apart. Because of the bowel obstruction associated with the withdrawn vaccine, a primary goal of the study was to determine whether RotaTeq was safe. Overall, 68,038 infants between six and 12 weeks participated, 34,035 in the vaccine group and 34,003 in the placebo group. All were monitored for serious adverse events, including intussusception.
During the study, infants who received the vaccine actually had a lower incidence of intussusception: 12 cases among vaccine recipients and 15 among those who received a placebo. No other significant side effects or complications were reported.
Rotateq also proved to be effective, nearly eliminating serious rotavirus-related gastroenteritis. The vaccine reduced rotavirus-related hospital admissions by 96 percent. In addition, RotaTeq reduced rotavirus-related emergency rooms visits by 94 percent, and doctor's office visits by 86 percent.
"The protective effect is strongest against the most severe disease,"
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Contact: Doug Gardner
GardneDA@evms.edu
757-446-6070
Eastern Virginia Medical School
4-Jan-2006