Results from a phase 2b trial testing a new malaria vaccine have been published revealing an impressive 77 percent efficacy, higher than any prior vaccine trialed. The vaccine is the first to reach a World Health Organization goal of at least 75 percent efficacy and recruitment on a larger phase 3 trial is now underway.
In 2019, after decades of development, a malaria vaccine called RTS,S began to be administered to children in Malawi, Ghana and Kenya. The massive pilot program is working to immunize over one million children after rigorous clinical trials found the vaccine to be up to 50 percent effective at reducing incidences of malaria.
While these efficacy rates were not as high as many researchers had hoped, the World Health Organization moved ahead with a large-scale pilot vaccination program exploring the real-world outcomes of the vaccine. The WHO has no current plans to expand the roll-out of RTS,S beyond this initial pilot project. In fact, the WHO’s Malaria Vaccination Technology Roadmap has previously set a target of 75 percent efficacy for any widely deployed malaria vaccine in the future.
A new vaccine, dubbed R21/MM, is the first to cross that 75-percent efficacy threshold. R21 is a modified version of the RTS,S malaria vaccine. It works in similar ways to its antecedent but deploys a different adjuvant, the compound added to vaccines to boost immune responses.
A study, published on The Lancet’s preprint server and yet to be peer-reviewed, is reporting the results of a large double-blind, randomized, controlled phase 2b trial conducted over several years in Nanoro, Burkina Faso.
The trial recruited 450 children aged between five and 17 months. Alongside a control group receiving a rabies vaccine, two different doses of vaccine were studied. Over a twelve-month follow-up the high-dose vaccine group reported 77 percent efficacy in preventing clinical malaria while the low-dose group saw 71 percent efficacy.
“These new results support our high expectations for the potential of this vaccine, which we believe is the first to reach the WHO’s goal of a vaccine for malaria with at least 75% efficacy,” says Adrian Hill, from the University of Oxford and co-author on the new study. “With the commitment by our commercial partner, the Serum Institute of India, to manufacture at least 200 million doses annually in the coming years, the vaccine has the potential to have major public health impact if licensure is achieved.”
There is still a long road ahead before this new vaccine comes close to large-scale use. A phase 3 trial is commencing now, spanning four African countries and enrolling close to 5,000 children.
However, the importance of developing an effective malaria vaccine cannot be understated. Over 400,000 people still die from malaria every year. Lynsey Bilsand, from vaccine research charity Wellcome, calls this new breakthrough “significant and exciting” in the ongoing battle against this major global health problem.
‘Despite global efforts against malaria, too many lives are still lost to this disease, especially babies and young children,” says Bilsand. “Vaccines could change this. This is an extremely promising result showing high efficacy of a safe, low-cost, scalable vaccine designed to reach the huge numbers of children who are most at risk of the devastating impact of Malaria.”
The new study was published on The Lancet’s pre-print server, SSRN.
Source: University of Oxford
