Two potential rotavirus vaccines tested
Rotavirus, a member of the reovirus family, is one of the world’s leading causes of childhood death. This virus causes acute gastroenteritis and diarrhea, resulting in 600,000 fatalities every year in children younger than 5. Most of these deaths occur in the developing world, where there is poor sanitation and medical care, but even in the United States, about 40 deaths every year in children are attributed to rotavirus. Additionally, there are about 70,000 hospitalizations and billions of dollars in health care costs and missed work days for parents due to infection with this virus—-so the virus still causes a significant financial burden, even in a developed country.A vaccine against the virus was first introduced in 1998 by Wyeth, with the name “RotaShield.” Based on a genetically engineered rhesus monkey rotavirus, the vaccine was withdrawn from the U.S. after only 11 months due to reports citing a potentially fatal intestinal blockage (intussusception) associated with use of the vaccine. Studies conducted following removal from the market showed that the risk of intussusception following vaccination with RotaShield was much lower than initially thought, and much lower than the risk of death from rotavirus, but the damage had been done and the virus remained shelved.
Two new vaccines may be able to take RotaShield’s place. Trials in a number of countries of these vaccines, GlaxoSmithKline’s Rotarix and Merck’s RotaTeq, showed that they worked well and had few side effects. In a trial involving 63,000 infants, the serially passaged, attenuated human rotavirus vaccine Rotarix reduced serious illness by 85% and hospitalizations for diarrhea by 42%. (Details here in the current issue of the New England Journal of Medicine). The RotaTaq vaccine, a genetically modified cow rotavirus, was given to 68,000 infants and was found to reduce severe disease by 98% and diarrhea-related hospitalizations by 63%. (Full study available here).
A current problem, however, is the cost of these vaccines. These new vaccines are projected to cost approximately $100 each, or more, putting them far out of the reach of most third world countries, where even $1 for a vaccine is often more than most people and the government can afford. More widespread use in countries that can afford them, such as the United States, could serve to drive these prices down, but this will still take time—-and meanwhile, over half a million children are dying each year from this virus. (To give some numbers for comparison, about 4 million babies are born each year in the U.S.--imagine waiting for a vaccine for a disease that killed 15% of them every year. ) Not surprisingly to anyone who follows global health issues, the Bill and Melinda Gates Foundation, among others, are working to accelerate this process, and get this vaccine to those who need it most.
Rotavirus, Vaccine, Virology, Global Health
