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Widespread testing begins on malaria vaccine
Mothers wait for their children to be vaccinated against malaria at the start of a pilot program at Mitundu Community Hospital, in Lilongwe, Malawi, on April 23, 2019.
With malaria deaths rebounding worldwide, a pilot program testing a new and fiercely debated malaria vaccine began on Tuesday in Malawi. Dr. Katherine O’Brien, the World Health Organization’s director of immunization, called the rollout “a historic moment in the fight against malaria,” and said the testing will soon expand to malarious regions of Ghana and Kenya. But the vaccine, known as RTS,S, or Mosquirix, has been in development for more than 30 years, and it has serious drawbacks that have led some experts to argue that it does not work well enough to spend millions of dollars pursuing.
Malaria kills about 450,000 people a year, most of them young African children. Over the last 15 years, the death rate has been reduced by more than half through extensive, donor-funded efforts to hand out free mosquito nets, spray homes with insecticide and treat people with a new generation of medicines. Nevertheless, deaths have increased again as money has run short, populations have grown, resistance to some new drugs has emerged and mosquitoes have expanded their ranges. Finding new weapons is crucial, experts agree, but making a malaria vaccine has proved challenging in the extreme.
The new vaccine has many weaknesses. It is inconvenient: a child must receive four injections before age 2, sometimes at intervals that do not match the routine vaccine schedules for most other diseases. And it is only partly effective. Testing in more than 10,000 African children from 2009 to 2014 showed that, even after four doses, the vaccine prevented only about 40 percent of detectable malaria infections. The vaccine reduced the occurrence of severe malaria by about 30 percent. It did not protect well against parasite strains that were poor genetic matches, raising a concern that, over time, parasites could evolve resistance to the vaccine as they have to drugs.
(Donald G. McNeil Jr. www.nytimes.com, 24.04.2019. Adaptado.)
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