MORE than half a million children a year in developing countries could be saved by new vaccines against rotavirus. Mexico will start using the first of the vaccines in 2005.
Rotavirus infects just about every child in the world by the time they are five years old. It is the most common cause of severe diarrhoea among children. But while only a handful of children die in rich countries, in poor countries the disease is often fatal.
The first rotavirus vaccine, called RotaShield, was withdrawn in October 1999 after being on the US market for only nine months, because it appeared to slightly increase the risk of intussusception, a treatable condition in which the bowel folds in on itself. Developing countries then refused to license RotaShield, even though the vaccine would have saved many more children than might have died from intussusception.
Advertisement
At least 2 million deaths could have been prevented, says Ruth Bishop of the Royal Children鈥檚 Hospital in Melbourne, Australia, who discovered rotavirus in 1973, and who still works on vaccine development. 鈥淭he RotaShield tragedy set us back five to ten years.鈥�
RotaShield was based on a rotavirus strain that infects monkeys. Now two alternative live vaccines have been developed by pharma giants GlaxoSmithKline and Merck. GSK鈥檚 Rotarix is a weakened version of the human virus. Merck鈥檚 RotaTeq is based on a strain from cows.
鈥淭hey鈥檙e biologically very different, and they act very differently in the body,鈥� says Paul Offit, the chief of infectious diseases at the Children鈥檚 Hospital of Philadelphia. And at a rotavirus conference in Mexico City last week, both companies announced that the preliminary results of phase III trials of the oral vaccines suggest that neither causes intussusception.
RotaTeq was tested in the US and is likely to be launched there in 2006. But GSK took a more controversial approach. Instead of jumping through the regulatory hoops in Europe or the US, GSK held almost all of its half-dozen trials involving 78,000 subjects in the developing world, in countries including Mexico, Brazil, South Africa and Malaysia.
鈥淲hen the news came out about RotaShield, we had to decide if we were going to cancel [our vaccine] programme or redouble our efforts,鈥� says Beatrice De Vos, director of clinical development at GSK Biologicals. 鈥淲e decided that the way to gain acceptance and overcome fears in the developing world was to work closely with them in developing the vaccine.鈥�
While Rotarix will be marketed in several countries in 2005, GSK has no immediate plans to request approval from the US Food and Drug Administration. That turns the usual system on its head. Drug companies usually make most of their profits in the US and Europe. GSK appears to be betting that the market in developing countries alone will be profitable, thanks to initiatives such as the Global Alliance for Vaccines and Immunization, backed by the Gates Foundation, which helps fund the purchase of vaccines.
Although GSK promises that Rotarix will be cheaper than RotaShield, which cost $38 per dose, some question whether it will be affordable. 鈥淓ither it costs 25 cents a dose or the poor countries can鈥檛 pay for it,鈥� says Isaias Raw, director of the Fundacao Butantan, a non-profit vaccine development institute in Brazil.
GSK could soon face competition, though. Bharat Biotech of Hyderabad, India, is in the early stages developing its own rotavirus vaccine and expects to start clinical trials in 2005. 鈥淚f it gets approval from the Indian authorities, I鈥檓 sure we can produce it for less than a dollar a dose,鈥� says Sai Prasad, manager of business development. 鈥淚t will be the first vaccine made in India by Indians, and affordable for Indians.鈥�