GlaxoSmithKline Plc’s experimental malaria vaccine safely reduced illness in African infants by more than half, a finding that’s a step toward its eventual use in preventing the deaths of as many as 800,000 children a year.
The shot, known as RTS,S, would be the first vaccine against malaria. It protected 56 percent of 6,000 children aged five months to 17 months old from developing symptoms 12 months after receiving their third dose and 47 percent from suffering severe malaria, according to data from a final-stage study published online today by the New England Journal of Medicine.
“The overall picture is this is a project that has the potential to halve malaria in young children,” David Schellenberg, one of the study’s authors and a professor of malaria and international health at the London School of Hygiene and Tropical Medicine in London, said in a telephone interview. “It’s an enormous achievement which has taken decades and huge amounts of resources.”
There were 225 million cases of malaria, a mosquito-borne parasite of the human liver and blood, globally in 2009, according to the World Health Organization. The illness causes fever, chills and flu-like symptoms, or shock, anemia and organ damage if untreated. Malaria is prevented now with insecticide-treated bed nets. Drugs are prescribed after infection.
About 781,000 people died from the disease in 2009, most of them children under the age of five in sub-Saharan Africa, according to the WHO.
The data published today are the first results from a study of 15,460 children aged as young as six weeks in seven African countries that began in March 2009.
Children were given either RTS,S or a non-malaria vaccine. The number of serious adverse events was about the same in each group, according to the researchers and London-based Glaxo. Eighteen percent of those receiving the experimental vaccine suffered a serious side effect, compared with 22 percent of those receiving the control vaccine, Glaxo said.
Results from a smaller, mid-stage trial published in 2007 showed the vaccine reduced new malaria infections -- as confirmed in blood tests -- in African infants by about two-thirds.
The vaccine’s level of protection ultimately needs to be higher, Eric Mouzin, a medical epidemiologist at the Roll Back Malaria Partnership, a network of malaria organizations based in Geneva, said in a telephone interview.
“Ideally you would want a vaccine to be 100 percent effective,” he said. “That’s not what we have at the moment. It doesn’t mean we won’t get it one day.”
Another researcher, Adrian Hill, director of the Jenner Institute in Oxford, England, said additional data in the study raised a question about whether the vaccine would prove worthwhile. The researchers found the vaccine was 35 percent effective against severe malaria after 11 months in a combined group of five- to 17-month-olds and six- to 12-week olds. That suggests the vaccine won’t be cost-effective against severe malaria in the younger group to whom it is designed to be given, making it “a complete non-starter,” Hill said.
He predicted Glaxo’s vaccine would probably be superseded by or used in combination with another within five years. Glaxo and the Bill & Melinda Gates Foundation, which contributed to the trial costs, aren’t emphasizing other vaccines to combat malaria because they have focused their resources on RTS,S, Hill said.
“We have better vaccines than RTS,S,” Hill said in a telephone interview. “There are a lot of vaccines in the clinic now that when combined with RTS,S get high levels of efficacy. We could do better. Why wait five years for millions more children to die?”
Meningitis, a bacterial infection of the membranes covering the brain and the spinal cord, was reported more frequently in the RTS,S-vaccinated group than in the control group, the researchers wrote. The older children were 5.5 times more likely to develop the illness and the younger children were four times more likely, they said. There didn’t appear to be a link to immunization, they said.
In an accompanying editorial, Nicholas J. White, a professor of tropical medicine at Mahidol University in Bangkok, wrote that the higher rate of meningitis in the RTS,S group needed to be better understood.
“There seems to be no plausible explanation for this, and it may well turn out to be a chance finding, but it cannot be ignored,” White wrote.
The new findings were announced at a Gates Foundation meeting of 300 malaria scientists, health researchers, policymakers, advocates and government leaders in Seattle. The foundation, the world’s richest charitable fund, has contributed more than $200 million toward the Malaria Vaccine Initiative of PATH, a Seattle-based public health charity.
“This is proof that it is possible to create a vaccine that is effective,” Microsoft Corp. Chairman Bill Gates said today in a statement. “If further results show that the effectiveness of RTS,S does not wane over time, it has the potential to protect millions of children and save thousands of lives.”
Glaxo has spent more than $300 million on developing and testing the vaccine and expects to spend a further $50 million to $100 million, the company said in a statement.
“This is a significant milestone on what has been a 25-year journey to develop the RTS,S vaccine, a journey which at the beginning many in the world believed was impossible,” Glaxo Chief Executive Officer Andrew Witty said today on a conference call.
Glaxo aims to file for regulatory approval in 2014 and bring the vaccine to market “as early as 2015,” Witty said. If approved, the Geneva-based WHO has said it would decide by 2015 whether to include the shot among its recommended childhood vaccines, which would enable it to be included in national immunization programs.
Glaxo hasn’t disclosed what it plans to charge for RTS,S, only that the eventual price would cover the cost of making it plus 5 percent, which the company has said it would reinvest in finding a second-generation malaria vaccine or vaccines for other neglected tropical diseases.
Results of the trial in six- to 12-week-old infants are expected by the end of 2012, Glaxo said. Researchers will follow the children to determine how many become ill up to 30 months after their third dose, to study the vaccine’s long-term protective effects. Those results should be available by the end of 2014, the company said.
“If the efficacy fell too low, you would have to do some careful cost-effectiveness analysis,” Schellenberg said.