World’s first malaria vaccine works in major trial

SEATTLE/LONDON,  (Reuters) – An experimental vaccine  from GlaxoSmithKline halved the risk of African children  getting malaria in a major clinical trial, making it likely to  become the world’s first shot against the deadly disease.
Final-stage trial data released today showed it gave   protection against clinical and severe malaria in five- to  17-month-olds in Africa, where the mosquito-borne disease kills  hundreds of thousands of children a year.

Joe Cohen, co-inventor of the vaccine, meets an RTS,S vaccine trial volunteer. (worldvision.org)
Joe Cohen, co-inventor of the vaccine, meets an RTS,S vaccine trial volunteer. (worldvision.org)

“These data bring us to the cusp of having the world’s first  malaria vaccine,” said Andrew Witty, chief executive of the  British drugmaker that developed the vaccine along with the  non-profit PATH Malaria Vaccine Initiative (MVI).
While hailing an unprecedented achievement, Witty, malaria  scientists and global health experts stressed that the vaccine  — known as RTS,S or Mosquirix — was no quick fix for  eradicating malaria. The new shot is less effective than others  against common infections like polio and measles.
“We would have wished that we could wipe it out, but I think  this is going to contribute to the control of malaria rather  than wiping it out,” Tsiri Agbenyega, a principal investigator  in the RTS,S trials in Ghana, told Reuters at a conference in  Seattle about the disease.
Malaria is endemic in more than 100 countries worldwide and  killed around 781,000 people in 2009, according to the World  Health Organisation.
Control measures such as insecticide-treated bednets, indoor  spraying and the use of combination anti-malaria drugs have  helped cut the numbers of malaria cases and deaths significantly  in recent years, but experts say an effective vaccine is vital  to complete the fight against the disease.
The new data, presented at the Bill & Melinda Gates  Foundation’s Malaria Forum conference in Seattle and published  simultaneously in the New England Journal of Medicine, were the  first from a final-stage Phase III clinical trial conducted at  11 trial sites in seven countries across sub-Saharan Africa.
The trial is still going on, but researchers who analysed  data from the first 6,000 children found that after 12 months of  follow-up, three doses of RTS,S reduced the risk of children  experiencing clinical malaria and severe malaria by 56 percent  and 47 percent respectively.
“We are very happy with the results. We have never been  closer to having a successful malaria vaccine,” said Christian  Loucq, director of PATH MVI, who was at the Seattle conference.
Loucq added that widespread use of insecticide-treated  bednets in the trial — by 75 percent of people taking part —  showed that RTS,S can provide significant protection on top of  other existing malaria control methods.
Results in babies aged six to 12 weeks are expected in a  year’s time and, if all goes well, GSK believes the vaccine  could reach the market in 2015.
Getting it to the African infants that need it will take a  concerted effort from international funders, such as the Gates  Foundation that helped pay for the research. Health experts say  it must be cheap enough to be cost-effective.
Witty declined to say if a course of three shots would cost  under $10 but told reporters RTS,S would be priced as low as  possible. The company has previously said it will charge only  the cost of manufacture plus a 5 percent mark-up, which will be  reinvested into tropical disease research.
“We are not going to make any money from this project,”  Witty said.

PARASITE IN SALIVA
Malaria is caused by a parasite carried in the saliva of  mosquitoes. The RTS,S vaccine is designed to kick in when the  parasite enters the human bloodstream after a mosquito bite. By  stimulating an immune response, it can prevent the parasite from  maturing and multiplying in the liver.
Without that immune response, the parasite gets back into  the bloodstream and infects red blood cells, leading to fever,  body aches and in some cases death.
RTS,S’s co-inventor Joe Cohen said the data were robust and  consistent with earlier trials which also showed around 50  percent efficacy. Side effects, including fever and  injection-site swelling, were similar in children given RTS,S  and a control vaccine.
After working for 24 years on developing the shot, he said  he was “very proud of what we have achieved”.
Some external commentators were cautious about the vaccine’s  potential — health experts normally like to see a success rate  of 80 percent plus in a vaccine — but said it was an important  development that should save many lives.
“We’re probably not there yet, but this is a really  important advance in science,” Peter Agre, director of the John  Hopkins Malaria Research Institute and a former Nobel prize  winner, told Reuters at the Seattle Malaria Forum.

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