The process of making vaccines for parasites is extremely challenging – but scientists might be on the cusp of major breakthroughs.
There was much celebration in January, when Cameroon became the first country in the world to roll out routine vaccination against malaria. In February, Burkina Faso followed suit.
“Control of malaria has not been going in a good direction, for a lot of different reasons,” explains Kate O’Brien, who directs the department of immunisation, vaccines and biologicals at the World Health Organization (WHO). Malaria cases are rising, and roughly 600,000 people die of malaria each year. Factors include climate change, conflict, the lingering effects of Covid-19 on health systems, and the tenacious adaptability of malaria-carrying mosquitoes. This has meant that the stalwarts of malaria prevention – insecticides sprayed indoors and bed nets treated with insecticides – are losing some of their punch.
Mass malaria vaccination adds one more tool to this package, and one that takes a completely different approach, says O’Brien. “Coming in with an immune-based approach is a very historic and important addition,” she says. In 2019 the RTS,S vaccine against malaria began pilots in Ghana, Kenya and Malawi, and in 2021 the WHO recommended it for use in children. The RTS,S vaccine was followed by the R21 vaccine.
Yet a related milestone has gone less heralded. RTS,S was the first-ever vaccine against a parasitic disease. While diseases caused by parasites are numerous and varied, as a group they are understudied and solutions are underfunded. Most of the neglected tropical diseases, including leishmaniasis and Chagas disease, are parasitic diseases, according to the WHO.