Malaria Vaccine Nears Finish Line

After decades of painstaking work, the first vaccine against malaria could be ready in the next few years. Last week, GlaxoSmithKline unveiled positive results from a Phase III study of its malaria vaccine candidate RTS,S, one of the final steps before asking regulators to recommend it for use in developing countries.

Malaria, a mosquito-transmitted infection caused by the Plasmodium falciparum parasite, kills approximately 660,000 people every year, many of them children in sub-Saharan Africa. In the study, which involved more than 15,000 children across seven African countries, RTS,S was shown to be 46% effective in preventing malaria in infants aged five to 17 months and 27% effective in babies aged six to 12 weeks. Although efficacy is low compared with other childhood vaccines, which typically offer at least 80% immunity, malaria is particularly challenging, says Johanna Daily, who studies malaria pathogenesis at Albert Einstein College of Medicine. Even given the limited efficacy, “this may be for some countries the piece that will help them decrease transmission,” she says.

“While we want to be careful about not getting ahead of the data, this trial continues to show that a malaria vaccine could potentially bring an important additional benefit beyond that provided by the tools already in use,” says David C. Kaslow, vice president of product development at the PATH Malaria Vaccine Initiative (MVI), GSK’s partner in RTS,S development.

The next big milestone for RTS,S will be the release next year of final data from the study, which could reveal more about long-term efficacy. In 2014, GSK will ask European regulators to weigh in on the vaccine’s efficacy, paving the way for the World Health Organization to make a policy recommendation. A rollout of RTS,S is unlikely before 2016, an MVI official says.

GSK and the Gates Foundation have together sunk $550 million into the project to date.