Malaria is a life-threatening infectious disease affecting humans and other animals. It is caused by parasites spread through the bites of infected female mosquitoes. In 2019, there were 229 million cases of malaria and 409,000 deaths caused by this disease worldwide (World Health Organization 2020: xiv-xv).

Multiple randomized controlled trials show that mass distribution of long-lasting insecticide-treated nets reduces malaria fevers and prevents deaths from the disease (GiveWell 2018a). Despite the existence of effective prevention methods, tens of millions of people are still unprotected from malaria, and the funding gap for net distributions is in the hundreds of millions of dollars.

The Against Malaria Foundation provides funding for distribution of bed nets to high-risk populations. GiveWell estimates that it costs $4.59 to purchase and distribute an AMF-funded net (GiveWell 2020), and that a marginal donation of $4,106 to AMF is expected to avert the death of a child under five (GiveWell 2020b; for caveats, see GiveWell 2017).

While distribution of nets is the most common method to combat malaria at present, there are other promising approaches. The Malaria Consortium works on preventing, controlling, and treating malaria and other communicable diseases in Africa and Asia. One intervention they carry out is seasonal malaria chemoprevention (SMC) programs, which seek to distribute preventive anti-malarial drugs to children under the age of five (GiveWell 2018b; 2020c).

In principle, malaria could be controlled, and ultimately eradicated, by means of an effective vaccine. RTS,S/AS01 (trade name Mosquirix) is a recombinant protein-based malaria vaccine approved for use by European regulators in July 2015. Among children aged 5–17 months who received 4 doses of RTS,S/AS01, efficacy was 36% over 4 years of follow-up (Laurens 2020). In October 2021, the World Health Organization endorsed RTS,S/AS01 for "widespread use" among children in October 2021, making it the first vaccine candidate to receive that recommendation (Piper 2021). The WHO decision was partly based on results from an ongoing pilot program started in 2019 intended to vaccinate 360,000 children per year in Malawi, Ghana and Kenya over a five-year period (World Health Organization 2021). A month before the WHO announcement, a randomized trial had found that a treatment combining antimalarial medication with a four-dose schedule of the RTS,S vaccine, culminating with a booster shot just before the most vulnerable season, was much more effective than either of those methods alone (Chandramohan et al. 2021). In 2020, a study using a standard model of malaria transmission estimated that 4.3 million cases and 22,000 deaths in children under five could be averted annually assuming 30 million people are vaccinated, provided areas with the highest malaria burden are prioritized (Hogan, Winskill & Ghani 2020).

Yet another approach to combat malaria is to eliminate the mosquito species responsible for spreading the disease, or to modify it genetically to render it incapable of carrying malaria. Gene drives—genetic modifications designed to spread through a population at higher-than-normal rates of inheritance—could achieve both of these goals. In 2016, Open Philanthropy made a grant to enable the formation of a working group to further investigate genetic modification as a form of malaria control (Open Philanthropy 2016), and the following year it made a $17.5 million grant to Target Malaria, a nonprofit research consortium working to develop gene drive technologies to eradicate malaria in sub-Saharan Africa (Open Philanthropy 2017).