A CHILD dies every minute from the severe diarrhoea associated with rotavirus infection. But two recently developed vaccines could slash the number of deaths. Both appear to reduce the severity of diarrhoea and the need for hospital visits.
GlaxoSmithKline and Merck, the manufacturers of the two vaccines, have also indicated they are willing to charge poor countries less for them. Combined with assistance from groups such as The Global Alliance for Vaccines and Immunization and the Bill and Melinda Gates Foundation, this should help make them accessible to those who need them most. 鈥淭his will make it to the mouths of poor children,鈥� says Miguel O鈥橰yan, an infectious disease specialist at the University of Chile in Santiago, who helped conduct the trial on GSK鈥檚 vaccine, Rotarix.
The search for an effective vaccine against rotavirus, which kills 500,000 people a year, has been going on since the mid-1970s. Rotashield, the first licensed vaccine, was released with much fanfare in 1998. But just over a year later the product was pulled from the market when it was discovered that in rare cases it triggered a bowel obstruction called intussusception in infants.
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鈥淢erck鈥檚 Rotateq reduced the number of hospital cases by 94.5 per cent and severe gastrointeritis by 98 per cent鈥�
Like Rotashield, both the new vaccines consist of a weakened live virus and are given orally, starting at age 2 months, alongside the combined diphtheria, pertussis (whooping cough) and tetanus vaccines. Neither appears to show any association with intussusception.
鈥淭hese are milestone results,鈥� says John Wecker of PATH, a non-profit organisation based in Seattle, Washington. PATH runs the Rotavirus Vaccine Program, which aims to speed up the development and introduction of rotavirus vaccine to countries in need. Wecker believes that these vaccines might halve the number of deaths from diarrhoea worldwide.
Rotarix is made from an attenuated human virus, and in a trial of 63,225 babies, mostly in Latin America, two doses of the vaccine given at least a month apart prevented severe gastroenteritis and reduced the need for hospital treatment by 85 per cent (The New England Journal of Medicine, vol 354, p 11).
Merck鈥檚 Rotateq, which is based on a bovine strain of rotavirus, reduced the number of hospital cases by 94.5 per cent and severe gastroenteritis by 98 per cent in a trial of 68,038 infants mainly in the US and Europe. It was given in three doses at least one month apart (The New England Journal of Medicine, vol 354, p 23).
GlaxoSmithKline has already struck a deal with the Brazilian government to charge $15 for two doses of Rotarix, and the firm has indicated that the price could be reduced for poorer countries. In Mexico, where Rotarix has already been licenced, it currently costs $100 for two doses. Wecker expects that developing nations such as India will in time produce their own rotavirus vaccines, putting further downward pressure on the price (快猫短视频, 19 February 2005, p 42).
But he cautions that experience with other oral vaccines such as that for polio suggests that they may not work as well in malnourished infants with a lot of gastrointestinal pathogens. Trials in Africa and Asia are still needed, he says.
