Leading #Malaria Vaccine Gets Mixed Reviews
▻http://www.nytimes.com/2015/10/24/health/malaria-vaccine-rtss-world-health-programme.html
The leading candidate for a malaria vaccine suffered some setbacks this week even as two World Health Organization expert panels recommended going ahead with pilot projects to test it further.
The medical charity Doctors Without Borders said it would not join any pilot projects, and a guest editorial in The New England Journal of Medicine said a new study, showing that the vaccine worked less well when parasites mutated, “should give pause” to efforts to deploy it.
The vaccine, known as RTS, S or Mosquirix, has been in development for nearly 30 years, and is further along in the approval process than any other candidate. But it is no panacea. In clinical trials, it was less than 40 percent effective even after four shots.
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The medical journal study, looking at blood samples taken from 4,600 vaccinated children in the last clinical trial, found that the vaccine worked only about half the time when it was a good genetic match for the parasites a child had, and only a third of the time in bad matches.
More than 90 percent of the time, the matches were bad. Malaria parasites are famous for evolving drug-resistant strains, and scientists have worried that changes could make them impervious to vaccines as well.
If RTS, S, is ever widely used, the editorial said, “the most prudent course” would be to work to improve it while using it only in areas where it is a good match.