This appendix supports our post, “Further Scaling Our Malaria Grantmaking,” and summarizes our current working view and uncertainties about various programs we may fund at the time of publication. Please note, these views are early, rest on research and conversations that are still underway, and will evolve as we learn more. We hope to post updates in the coming months.
Insecticide-treated nets (ITNs)
An insecticide-treated net (ITN) is a net that has been treated with insecticide to kill and repel the mosquitoes that transmit malaria. In most nets now distributed, the insecticide is incorporated into or bound around the fibers and is designed to withstand some amount of washing. For more, see our intervention report on mass distribution of ITNs.
Delivery. WHO recommends mass campaigns that distribute one net per 1.8 people at risk, normally repeated every three years, alongside continuous ("routine") distribution, particularly through antenatal care and childhood immunization visits.1 In most high-burden countries, campaigns run approximately every 36 months; DRC's national target is every 30 months.2 GiveWell has funded mass campaigns at large scale for many years, mainly through the Against Malaria Foundation.3 Our 2026 grant to AMF for DRC campaigns includes funding for campaigns 24 months apart in up to five higher-burden provinces, in addition to support for campaigns 30 months apart for the rest of the country, in part because we believe nets degrade more quickly in DRC than in some other settings.4
Evidence. A Cochrane review of trials conducted between 1987 and 2001 found that ITNs reduced all-cause child mortality by 17% compared with no nets (rate ratio 0.83, 95% CI 0.77 to 0.89).5 As an example, in DRC, we estimate that each year of effective protection from a net reduces a child's risk of dying from malaria by between 24% and 56%, depending on location, with baseline malaria mortality, net durability, and net use as the main drivers of that range.6 We estimate nets provide effective protection for around two years in most countries (range roughly 1.2 to 2 years).7 More frequent campaigns would aim to reduce the proportion of children without coverage during that third year. We are not aware of trials comparing two-year with three-year cycles. For continuous delivery, we rely principally on the general evidence that nets work; we are not aware of randomized evidence for the effectiveness of the delivery channels themselves, but are considering funding further evidence generation in this area.8
Our current view. We believe ITN campaigns every three years are highly cost-effective in many areas with substantial malaria burden, due to their low cost per person protected, high effect size, high achieved coverage, and relatively long duration of protection. The main variables that affect our assessment of cost-effectiveness in a given area include malaria burden, net use rates, use of an effective net type, and expected durability of nets. There are additional net distribution modalities that we are considering supporting, but about which we are less confident:
- Campaigns every two years: Campaigns at shorter intervals, such as every two years, are likely above our cost-effectiveness bar in a subset of the areas where we consider campaigns every three years cost-effective. We think more frequent campaigns would effectively increase coverage, and the settings in which this would be cost-effective are mainly where malaria burden is particularly high, where nets wear out quickly, and where there are limited alternative sources of effective nets.
- Continuous delivery: Delivery through continuous channels could be above our cost-effectiveness bar in some contexts, but we are much less certain about this than we are for our estimates of campaign cost-effectiveness. The cost-effectiveness of this approach is likely to depend on how well clinics and supply chains function, and we are not sure how many health systems can execute this well enough to achieve high coverage.
Key uncertainties. How long nets, particularly dual-active-ingredient (dual-AI) nets, last in households in different settings; whether national malaria programs can, and would like to, run campaigns more often than every three years; subnational variation in malaria burden; and how many people campaigns and routine channels actually reach. We expect additional independent coverage surveys and durability data to improve our understanding of some of these factors.
Seasonal malaria chemoprevention (SMC)
SMC campaigns give children monthly courses of antimalarial drugs, typically sulfadoxine-pyrimethamine plus amodiaquine (SPAQ), during the season of peak malaria transmission in places where malaria is highly seasonal. Each course is intended to clear any infection a child already has, and provide additional protection for around four weeks afterward. The program is typically delivered via door-to-door distribution by trained campaign workers, targeting children 3-59 months old. For more, see our intervention report on SMC. The 2025 World Malaria Report estimates that SMC programs reached 54 million children in 2024 across 20 countries in Africa, and GiveWell has directed more than $500 million to SMC programs, mostly through Malaria Consortium.9
Delivery. WHO's original recommendation allowed at most four monthly cycles and was limited to young children in the Sahel. Later updates included implementation guidance for up to six cycles, removed geographic restrictions, and extended eligibility to older children where they are at high risk of severe malaria.10 Burkina Faso, Nigeria, and Uganda are among the countries that now deliver five cycles in areas where the season is longer.11 We are currently investigating whether there could be opportunities to expand SMC delivery. Variations we are exploring include increasing the number of monthly cycles in a given location, using alternative drugs in settings with high resistance to sulfadoxine-pyrimethamine (SP) and/or amodiaquine (AQ), targeting older children through campaigns or school-based delivery, and providing chemoprevention in areas where transmission continues year-round ("perennial" areas). At this point we are very uncertain about the safety, feasibility, and cost-effectiveness of these ideas.
Evidence. A Cochrane review found SMC reduced clinical malaria episodes in young children by about three-quarters (rate ratio 0.26, 95% CI 0.17 to 0.38), and our update of this meta-analysis to incorporate newer studies resulted in a similar effect size. The trials were too small to show an effect on all-cause mortality but showed a similar reduction in severe disease.12 The evidence base for the various program adaptations mentioned above is more limited, and in some cases (e.g., campaigns in perennial settings) we think evidence for effectiveness at scale may not exist. However, we have just begun reviewing the evidence for these program adaptations.
Our current view. We believe many SMC programs are highly cost-effective due to the large effect size on clinical and severe malaria, high malaria-attributable mortality rates, a large proportion of annual burden occurring during the months when SMC is delivered, and a low-to-moderate cost per child reached.13 However, there are a number of factors that could lead to a particular program being more or less cost-effective, including the level of drug resistance, economies of scale, and level of adherence to the full three-dose regimen for each monthly course.14
We are more uncertain about the cost-effectiveness, feasibility, and safety of the various program adaptations we're considering:
- Additional cycles: Increasing the number of monthly cycles delivered through existing campaigns could be cost-effective in less markedly seasonal settings, where additional cycles could still protect children from a moderate malaria risk. However, we're not confident about how many settings might fit these criteria and whether it is safe and feasible to provide more than five cycles of SPAQ.
- Alternative drugs in settings with high SP and/or AQ resistance: Chemoprevention with different drugs could be cost-effective in settings where burden is high but SPAQ efficacy is limited due to high resistance. However, limiting factors could include drug costs and the impact on choice of drugs for malaria treatment.15
- Older children: We view the primary benefit of chemoprevention for older children as reducing the risk of malaria transmission to younger children. However, there is limited evidence on the size of this transmission effect and the marginal cost of reaching older children.
- Chemoprevention in perennial areas: We are considering two possible methods of expanding chemoprevention in areas with perennial malaria transmission, though we remain highly uncertain about each:
- One option is perennial malaria chemoprevention (PMC). Unlike a campaign, PMC is the routine provision of antimalarial drugs (typically SP) to children attending immunization visits in perennial settings. This is clearly in line with WHO guidelines.16 However, our initial view is that the cost-effectiveness of PMC may be limited by low routine immunization coverage, a smaller target population, low efficacy of SP alone at reducing cases of malaria,17 and an inability to time the intervention to months of relatively higher transmission. We are continuing to explore PMC as a potential funding opportunity, though it remains a lower priority than other chemoprevention programs.
- Alternatively, we think it's plausible that chemoprevention campaigns targeting young children could be a cost-effective program even in settings without seasonal malaria transmission. However, we are not aware of any evidence on this program, are concerned that it may lead to a deferral of malaria cases to non-campaign months rather than preventing them, and believe it is less clearly aligned with WHO recommendations.
Malaria vaccines
Two falciparum malaria vaccines, RTS,S/AS01 and R21/Matrix-M, are recommended by WHO for children in malaria-endemic areas, prioritizing areas of moderate and high transmission.18 Both are pre-erythrocytic vaccines: they induce antibodies which block the Plasmodium falciparum parasite before it enters the liver, reducing the number of parasites that establish an infection, and thus protecting against subsequent illness.19 Protection is highest in the first months after three initial priming doses, and again after a booster dose.20
Delivery. WHO recommends four doses from five months of age: a primary series of three doses at least four weeks apart, then a fourth dose 6 to 18 months later, usually through routine immunization.21 In highly seasonal areas, countries may give the fourth and later annual doses just before the transmission season.22 In these areas, delivery can either be via campaigns or via routine immunization.23
Evidence. Large, high-quality randomized trials have shown that both RTS,S and R21 reduce clinical malaria by 50% or more in the 12 months after the initial priming doses.24 Randomized trials of RTS,S showed that a booster dose given around 18 months after the initial three priming doses gave additional protection (around 25%) against clinical malaria over 12 months.25 Evidence on the impact of yearly seasonal boosters comes from one large randomized trial in Burkina Faso and Mali, where seasonal RTS,S boosters had similar protective efficacy as SMC with SPAQ in preventing clinical malaria. SMC and seasonal boosters given together reduced clinical malaria by around 60% as compared to SMC alone.26
An evaluation of the cluster-randomized introduction of RTS,S through routine immunization in Ghana, Kenya, and Malawi estimated that all-cause mortality (excluding injury) among age-eligible children fell by 13% (95% CI 3% to 23%).27
Our current view. We think funding procurement and delivery costs for the malaria vaccine via routine immunization will be highly cost-effective in many places. Vaccination via campaigns or outreach programs, or seasonal booster campaigns could also be cost-effective, depending on coverage of the first three priming doses, additional delivery costs, and operational feasibility.
Key uncertainties. For routine vaccination, a key uncertainty is what share of children programs will be able to reach with the first three doses. For vaccination campaigns, we are unsure about whether governments want campaigns running alongside the routine system; we also think the cost-effectiveness of campaigns will depend heavily on how much coverage routine systems achieve. We may look to learn more about these from pilots with strong monitoring, conversations with national programs, and campaign coverage surveys.
Case management by community health workers (integrated community case management, iCCM)
This program aims to bring effective treatment for malaria and other common childhood illnesses close to home using community health workers (CHWs). CHWs are lay health workers, usually recruited from the community they serve. In integrated community case management (iCCM), CHWs typically treat the three leading infectious causes of death in young children: malaria, which they confirm with a rapid diagnostic test (RDT) and treat with an artemisinin-based combination therapy (ACT); diarrhea, treated with oral rehydration salts (ORS) and zinc; and pneumonia, treated with antibiotics.28
Delivery. WHO's malaria strategy says national programs "should expand integrated community case management of malaria, pneumonia and diarrhoea, with a focus on children under 5 years of age.”29 We have primarily been researching an integrated program because our impression from conversations with health systems experts was that one platform delivering several services is more likely to build community trust and improve adherence to negative test results. GiveWell has not funded iCCM programs at scale, though we have investigated them in the past.30
Evidence. The drugs CHWs could deliver to treat malaria are highly effective. Artemisinin-based combination therapies (ACTs) are the first-line treatment throughout Africa.31 A systematic review found that the protective efficacy of using prompt ACT treatment for uncomplicated malaria was over 99% in children aged 1 to 23 months.32
Evidence that iCCM programs reduce child mortality, however, is weaker and more heterogeneous. GiveWell’s 2016 review found two randomized controlled trials (RCTs): one in Ghana found a 44% reduction (rate ratio 0.56, 95% CI 0.41 to 0.76) over six months of follow-up, while one in Burkina Faso found no significant effect (0.95, 95% CI 0.57 to 1.59).33 We believe some recent evidence suggests that mortality effects may be more difficult to achieve at scale than in smaller, more intense implementations, though the evidence is not uniform, and we remain uncertain about what aspects of program implementation are most important.34
Our current view. We think iCCM for malaria, diarrhea, and pneumonia could be above our cost-effectiveness bar in many settings, though we have more uncertainties about this than ITNs, SMC, or vaccination. We think cost-effectiveness depends most on three things:
- How many additional children get effective treatment, which depends on how many would get it anyway and how much CHWs improve on that, particularly at scale
- The cost of the program per CHW
- How much malaria burden remains after prevention programs are implemented, since treatment can only avert deaths that prevention has not already averted
Key uncertainties. We are uncertain about whether CHW programs raise effective treatment coverage at scale, and what implementation intensity is required to do so (e.g., pay, density, supervision, and supply chain supports required); what it costs to run a program that works, and how much of this existing funding already covers; and what components we would fund. We expect that further discussions with experts and further research will help shape our view.
Spatial emanators
Spatial emanators (SEs) are small devices hung inside homes that release insecticide into the air, repelling mosquitoes and stopping them from finding and biting people.35 They need little action by the people they protect, and could provide protection during hours spent indoors but outside a bed net, such as the early evening and morning.36 The two WHO-prequalified devices release transfluthrin, a pyrethroid, the same class of insecticide used in standard bed nets.37
Delivery. In August 2025, WHO conditionally recommended indoor spatial emanators as a supplement to ITNs.38 It also prequalified two SC Johnson products: Mosquito Shield, which lasts up to one month, and Guardian, which lasts up to 12 months.39 In May 2026, the Global Fund, the US government, and SC Johnson announced a partnership to protect at least 60 million people with Guardian by 2028.40
GiveWell has not funded the distribution of spatial emanators. However, we have funded monitoring and evaluation (M&E) of distributions taking place under this partnership: Clinton Health Access Initiative (CHAI) is conducting M&E in Burkina Faso and Sierra Leone, and PATH in the Democratic Republic of the Congo. Through our ongoing Request for Information, we are also exploring whether to fund an RCT of spatial emanators in West or Central Africa.
Evidence. Two randomized trials in Africa measured malaria outcomes from emanators used alongside nets, and both tested Mosquito Shield. In Busia County, Kenya, an area with high transmission, insecticide resistance, and universal net coverage, emanators reduced first-time malaria infections by 33.4% (95% CI 11.1% to 50.1%) and all new infections by 32.1% (95% CI 15.9% to 45.2%).41 A similar trial in Mali found no effect on first-time infection (protective efficacy -3.1%, 95% CI -32.2% to 19.6%).42 We think it is likely that the true effect of SEs is closer to the Kenya result than the Mali result because we believe there may have been implementation issues with the Mali trial, but we are not certain about this: we think there is some chance that spatial emanators do not meaningfully reduce malaria infection incidence in high-burden settings. We are not aware of randomized trials of Guardian with clinical malaria outcomes, or of trials of emanators used without nets.
Our current view. We are very uncertain about the cost-effectiveness of spatial emanators. We think it is possible they are highly cost-effective in some contexts, but we are much less confident about this than we are for ITNs, SMC, and malaria vaccination programs.
Key uncertainties. We are unsure how effective spatial emanators, particularly Guardian, are at reducing malaria deaths among children under five, whether used alongside nets or on their own. We are unsure about this for several reasons: the RCTs in Kenya and Mali produced conflicting results; both trials tested Mosquito Shield, whereas we would expect to fund the longer-lasting Guardian; and no RCTs have tested standalone use.
It is also unclear how well the trial results will translate to real-world settings, where coverage and adherence may be lower. We don’t yet know how long emanators keep providing protection once they are in homes. Households given emanators might also use their nets less, which could cause harm if emanators protect less well than nets.
Finally, procurement and distribution costs are uncertain, though we expect them to fall at scale.
Indoor residual spraying (IRS)
IRS involves spraying long-lasting insecticide on the inside walls of homes, where many malaria-carrying mosquitoes rest, so that mosquitoes are killed before they can transmit malaria.43 WHO lists IRS, alongside ITNs, as a core vector control intervention for populations at risk of malaria.44
Evidence. WHO currently recommends against deploying IRS in addition to ITNs in most settings, advising programs instead to prioritize optimal coverage with one intervention or the other.45 In most cases we expect that dual-AI nets will be more cost-effective than IRS (see “Our current view” below), so we would generally expect to fund nets first. We’ve therefore initially prioritized understanding the evidence base for what IRS adds where dual-AI nets are already in place, so this section focuses on that comparison. We have not yet looked in depth at whether there are specific settings where using IRS instead of ITNs would be more cost-effective.
Two non-randomized studies suggest IRS may substantially reduce malaria incidence in comparison to nets alone. In northern Uganda, a quasi-experimental study found that pirimiphos-methyl IRS was associated with 73% lower malaria incidence, relative to the trend in nets-only control areas; some sites had dual-AI nets and the rest had piperonyl butoxide (PBO) nets.46 In Côte d’Ivoire, malaria cases rose after IRS was withdrawn and replaced with dual-AI nets, though the nets arrived late and the study had no control sites.47
Randomized evidence comes from settings with older net types (where we would generally expect IRS to have a larger additional impact than when paired with dual-AI nets, and where the effect is potentially due to use of an effective insecticide versus a non-effective insecticide, rather than to the intervention modality—that is, IRS vs. ITN—itself) and is mixed. In a trial in Tanzania, adding pirimiphos-methyl IRS to PBO nets gave no clear benefit over PBO nets alone.48 In a trial in Burkina Faso and Côte d’Ivoire, adding pirimiphos-methyl IRS to nets reduced malaria incidence by about 23%.49 Against standard pyrethroid nets, a 2022 Cochrane review found that adding non-pyrethroid-like IRS reduced parasite prevalence (risk ratio 0.61, 95% CI 0.42 to 0.88; four trials; high-certainty evidence), though the effect on incidence was imprecise (rate ratio 0.86, 95% CI 0.61 to 1.23; low-certainty evidence).50
Observational evidence from settings with pyrethroid nets or no nets shows very large effects in some places. In Tororo, Uganda, mass net distribution plus six rounds of IRS were associated with a fall in infective bites from 129 per person per year to zero,51 and malaria resurged when the program switched to a less effective insecticide.52 On Bioko Island, IRS was followed by near elimination of infectious An. gambiae and An. funestus.53 Because standard nets are less effective than dual-AI nets in areas where mosquitoes are resistant to the standard insecticides, we think these results likely overstate how much IRS would add where we would fund it.
Overall, we think IRS’s added value on top of dual-AI nets is highly uncertain, with plausible estimates ranging from close to no effect to very large effects. Some of this range likely reflects real differences between settings, since IRS’s impact depends on factors such as which mosquito species drive transmission and whether they are susceptible to the insecticide used.54
Our current view. While we think IRS is likely to be useful in specific contexts, our current best guess is that there is a lower volume of cost-effective IRS opportunities compared to ITNs, SMC, and vaccination programs, and we have not included IRS in our current core list of prevention programs we think we are most likely to fund at scale. This is primarily because:
- Due to higher costs per person protected of IRS compared to dual-AI nets,55 our best guess is that we would likely prioritize dual-AI nets before funding IRS in most places. This reduces the malaria burden that IRS would prevent, which makes IRS less cost-effective; as discussed above, there is also less evidence about the effectiveness of IRS in such contexts.
- Additionally, we are unsure whether its operational demands would draw capacity away from other malaria priorities, and how many areas it could realistically reach. For example, IRS may not be feasible where there are security concerns or where roads can’t take spray vehicles.
- Finally, even in contexts with very high malaria burden, we are aware of some evidence that malaria can resurge quickly when IRS is removed56 — though we’re unsure if this resurgence goes above the pre-IRS baseline. We would want to take this into consideration in situations where we can only guarantee funding for a limited period of time.
Even so, we think IRS may be cost-effective in some contexts, such as where malaria cases are surging and in some humanitarian emergencies.
Key uncertainties. We would become more positive about IRS if randomized trials showed that it substantially reduces malaria transmission in the context of high coverage of dual-AI nets, and if we could reliably predict where it would work best, for example from local vector species and insecticide susceptibility. Better evidence on rebound could also change our view, particularly if it showed that deaths do not rise much above pre-IRS levels once spraying stops, or that the risk is no greater than for other intensive malaria programs. It would also matter less if we or others could commit to funding IRS for longer. Finally, clearer evidence on where IRS is operationally feasible would help us judge how widely it could be used.
Preliminary approach to new tools
What we mean by new tools. These are products and strategies that either are not yet available or are available now but have not yet been broadly implemented.
How we assessed potential new tools. We identified 18 potential new tools and, drawing on expert calls, trial registries, and desk research, briefly evaluated whether each could be available, WHO-recommended, and supported by evidence before 2032. For 10 tools we thought could plausibly meet these criteria, we estimated how much we could cost-effectively spend on each tool, discounting for the chance that tool development or evidence generation fails, that resistance emerges or fails to emerge, or that countries decline to adopt the tool.
Our current view. We think the 10 new tools we’ve looked into could potentially be highly cost-effective, but our eventual decision about whether to support widespread adoption of any tools will depend on additional evidence that we expect to emerge over the next five years.
Specifically, when and whether we fund these tools will depend on:
- Whether and when each tool becomes available
- Results of further evidence generation
- Rate of development and spread of insecticide and drug resistance
- Other changes in the world between now and when the tools become available (e.g., changes in malaria burden and changes in funding available from other actors)
- Additional GiveWell research on the cost-effectiveness and feasibility of supporting and deploying each tool
- Government interest in adopting new tools
Below we list the new tools contributing to our current estimates of expected room for more funding, along with what we see as the main barriers to GiveWell funding these tools immediately.
- Spatial emanators: We’d like more evidence of their effectiveness in high-burden settings (see above).
- New options (repurposing existing drugs) for chemoprevention in children under five: We’d need more evidence on effectiveness and safety of alternative drugs.
- ACT and RDT subsidies for the private sector: We are uncertain about the extent of gaps in the availability of quality ACTs and RDTs in the private sector as well as the best way to support this strategy.
- New RDTs: We are uncertain about the settings in which support is likely to be cost-effective.
- New options (repurposing existing drugs) for chemoprevention in pregnant women: More evidence is needed on effectiveness and safety of alternative drugs.
- Next-generation ITNs: These are not yet available.
- New treatments for severe malaria: These are not yet available.
- Rectal artesunate: We are unsure of the best way to implement this.
- New strategies to slow the emergence of antimalarial drug resistance: We are uncertain about how to evaluate the benefits of slowing drug resistance. Among the strategies are:
- Multiple first-line therapies (available now)
- Triple ACTs (not yet available)
- Ganaplacide/lumefantrine (GanLum; not yet available)
- Single low-dose primaquine (evidence is still needed on whether this strategy can mitigate spread of artemisinin resistance in high-transmission settings)
- Insecticide-treated babywraps: These are not yet widely available.
We also considered the following new tools but did not include them in our expected room for more funding because we thought they were (1) unlikely to be available before 2032, (2) unlikely to be cost-effective, and/or (3) likely to replace other existing or new tools at minimal additional cost (so unlikely to change the total funding needs significantly):
- Monoclonal antibodies for malaria prevention
- New options for chemoprevention in children under two years old
- Tools for reducing outdoor malaria transmission
- Next-generation malaria vaccines
- Long-acting injectable chemoprevention drugs
- Next-generation IRS
- Newly developed seasonal malaria chemoprevention medications
- Gene drive (genetically modified mosquitoes)
How we expect to fund this. We expect that early funding would mostly go to evidence generation and potentially to support WHO guideline development where a tool is waiting on a recommendation. Once a tool is recommended, we might buy it directly or support its use through market shaping, such as volume guarantees (commitments to buy a set quantity at a set price).
Malaria supply chain support
The programs we've outlined above generally involve funding the procurement and/or distribution of health commodities by campaigns or CHWs. Weakness in the supply chains that underpin these programs can reduce the impact of programs with otherwise strong theories of change.
Supply chain support could increase the odds that the programs we fund reach those who need them in a timely manner. This type of support is complementary to the other malaria investments GiveWell may make and might matter more with a larger malaria investment envelope that will channel a greater volume of commodities through health systems and supply chains that are already stretched thin. We are interested in efforts that can improve the functioning of supply chains, but we have spent much less time investigating this investment area compared to programs like ITNs or SMC. We do not currently have estimates of the room for funding or cost-effectiveness of malaria supply chain support.
How we assess supply chain support and existing work GiveWell has done. GiveWell has not conducted in-depth research into malaria supply chain gaps or intervention options. An expert in our network flagged that supply chain constraints can reduce the effectiveness of existing programs and limit the absorptive capacity of new programs we might support.57 We have previously worked with CHAI and PATH to identify and respond to emergency stock-outs of malaria case management commodities in several countries,58 and have set up a backstop fund with CHAI to proactively respond to malaria case management gaps. While these grants were not about supply-chain strengthening, our work on them suggests that preventing stock-outs may be highly cost-effective. We are currently working with partners to learn about supply chain constraints and explore potential intervention options.59
Our current view. We think that targeted supply chain support may be a cost-effective way to deploy additional malaria funding, but we remain uncertain because there is limited evidence connecting supply chain support to improved health outcomes (in part because it is hard to run high-quality evaluations of these types of interventions that can detect downstream effects on health outcomes).
It is difficult to generalize what supply chain interventions work, as supply chain constraints tend to be context-specific. We are hoping to investigate this space further and develop hypotheses that can guide our malaria supply chain support work. While the exact shape and magnitude of our supply chain work remains highly uncertain, we think that this portfolio could involve investing in one or more of the following domains:
- Plugging gaps in warehousing and distribution costs for key commodities
- Systems to improve health product inventory management and logistics
- Providing technical assistance and tools to assist in the forecasting of health product needs
- Private sector supply chain support
- Health product quality assurance
Sources
- 1
See the sections on what ITNs are and how ITN distributions work in our report on insecticide-treated nets.
- 2
See our August 2026 post on our DRC nets grant and its footnote 12.
- 3
See this section of our report on insecticide-treated nets and our August 2026 post on our DRC nets grant.
- 4
You can see more about this grant in the August 2026 blog post on the DRC nets grant mentioned above.
- 5
“Insecticide-treated nets reduce child mortality from all causes by 17% compared to no nets (rate ratio 0.83, 95% CI 0.77 to 0.89; 5 trials, 200,833 participants, high-certainty evidence).” Pryce, Richardson, and Lengeler, 2018, p. 2.
- 6
This was based on our analysis of Pryce et al. 2018 (see footnote 5). See the section "Nets significantly reduce child deaths in DRC" in our post on our DRC nets grant.
- 7
See this section of our report on insecticide-treated nets. This range covers Chad, DRC, Guinea, Nigeria, South Sudan, Togo, and Uganda. You can find our analysis for estimates by country on this row of our cost-effectiveness analysis.
- 8
In May 2026, we requested proposals for technical assistance to strengthen continuous net distribution, with monitoring and evaluation required to measure the effect on coverage. See our request for information on malaria pilot programs, section 2.1, "Continuous net distribution - technical assistance." The request is announced in our blog post, "GiveWell Opens RFI for Malaria Pilots and Research".
- 9
- See our May 2026 post on our malaria research.
- “SMC is currently being implemented in 20 countries in sub-Saharan Africa (Table 5.1). … As shown in Table 5.1, the average number of children treated per cycle of SMC has steadily increased from about 0.2 million in 2012 to 54 million in 2024.” World Health Organization, World malaria report 2025, p. 73.
- 10
- “The original recommendation stated that a maximum of 4 monthly doses of SMC should be given during the malaria transmission season. [...] The original recommendation restricted SMC use to the Sahel subregion of Africa [...] The updated recommendation recognizes that countries in other parts of Africa with highly seasonal variation in malaria burden could also benefit from SMC. [...] The updated guidance states that SMC should be given during peak malaria transmission season, without defining the specific number of monthly cycles. [...] While the original recommendation restricted SMC use to children less than 6 years of age, the new recommendation recommends this intervention for children at high risk of severe malaria, which may extend to older children in some locations.” World Health Organization, "Updated WHO recommendations for malaria chemoprevention among children and pregnant women" 2022.
- "Current evidence supports monthly administration of SMC for 3-4 cycles in shorter transmission settings, and up to six cycles have been evaluated in settings with longer transmission seasons" World Health Organization, WHO guidelines for malaria, 10 September 2026, p. 116.
- 11
See this section of our report on seasonal malaria chemoprevention, including its footnote 16.
- 12
- “IPTc prevents approximately three quarters of all clinical malaria episodes (rate ratio 0.26; 95% CI 0.17 to 0.38; 9321 participants, six trials, high quality evidence) and a similar proportion of severe malaria episodes (rate ratio 0.27, 95% CI 0.10 to 0.76 [...]).” Meremikwu et al. 2012, p. 2.
- Our update of the Cochrane meta-analysis with newer studies found a very similar effect on clinical malaria (rate ratio 0.25; 95% CI 0.18 to 0.37). See this section of our report on seasonal malaria chemoprevention.
- 13
See this section of our report on seasonal malaria chemoprevention for more on why we think it is cost-effective.
- 14
Our cost-effectiveness analysis adjusts for children not completing the full course and for the development of drug resistance. See the sections on the number of cycles delivered and offsetting impacts in our report on seasonal malaria chemoprevention.
- 15
- We have funded an individually randomized trial of seasonal malaria chemoprevention using hydroxychloroquine vs amodiaquine vs placebo with or without sulfadoxine-pyrimethamine in 6,900 children under 5 years in Malawi. The results are expected in July 2027 and will inform optimal chemoprevention drug choice for SMC in East and Southern Africa.
- We put out a request for proposals for alternative drugs for chemoprevention in West Africa in May this year. Successful proposals will be selected before the end of the year.
- 16
The WHO guidelines recommend PMC for young children in areas of moderate to high perennial malaria transmission, delivered mainly through routine immunization visits. See WHO, WHO guidelines for malaria, 2026, pp. 110-115.
- 17
"PMC probably reduces the risk of clinical malaria compared to placebo or no PMC when using SP (rate ratio: 0.78; 95% CI: 0.69-0.88)." World Health Organization, WHO guidelines for malaria, 2026, p. 112. By comparison, SMC with SPAQ "reduced the risk of clinical malaria by almost three quarters (risk ratio: 0.27; 95% CI: 0.25-0.29)." World Health Organization, WHO guidelines for malaria, 2026, p. 116.
- 18
“Two malaria vaccines are WHO-prequalified and recommended for use: RTS,S/AS01 and R21/Matrix-M. [...] WHO recommends the use of malaria vaccines for the prevention of P. falciparum malaria in children living in malaria-endemic areas, prioritizing areas of moderate and high transmission” WHO guidelines for malaria, 2026, p. 154-155. See also WHO, Malaria vaccine position paper, May 2024.
- 19
“Both are pre-erythrocytic vaccines that prevent P. falciparum infection and subsequent illness and death in children.” WHO guidelines for malaria, 2026, p. 154. See also WHO, Malaria vaccine position paper, May 2024.
- 20
- “Because vaccine efficacy is highest in the first months after vaccination, the fourth dose can be given just prior to seasonal peaks in malaria transmission to optimize vaccine efficacy.” WHO guidelines for malaria, 2026, p. 156. See also WHO, Malaria vaccine position paper, May 2024.
-
You can read more about malaria vaccines in our intervention report, though this is our view in 2022, which has since changed.
- 21
“Malaria vaccines should be provided in a four-dose schedule in children from 5 months of age for the reduction of malaria disease and burden. […] The minimum interval between any doses is four weeks; however, to achieve prolonged protection, the fourth dose should be given 6–18 months after the third dose” WHO guidelines for malaria, 2026, p. 156. See also WHO, Malaria vaccine position paper, May 2024.
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"Alternatively, because vaccine efficacy is highest in the first months after vaccination, the fourth dose can be given just prior to seasonal peaks in malaria transmission to optimize vaccine efficacy.
A fifth dose, given one year after the fourth dose, may be provided in areas with highly seasonal transmission or where malaria risk remains high during the third year of life and beyond, depending on a local assessment of feasibility and cost-effectiveness." WHO guidelines for malaria, 2026, p. 16. See also WHO, Malaria vaccine position paper, May 2024.
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“Both fixed vaccination sites at health care facilities and opportunities for mobile vaccination delivery or outreach services should be considered. To increase uptake, periodic mass vaccination campaigns or periodic intensified routine immunization activities can be deployed” WHO guidelines for malaria, 2026, p. 154. See also WHO, Malaria vaccine position paper, May 2024.
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“In a large Phase 3 trial, age-based vaccination with three doses of RTS,S/AS01 resulted in significant reductions in clinical malaria (51%; 95% CI: 47–55) and severe malaria (45%; 95% CI: 22–60) during 12 months of follow-up after the third dose. … The R21/Matrix-M malaria vaccine has also demonstrated efficacy in a multi-centre Phase 3 trial; when given through an age-based approach, there was a significant reduction in clinical malaria (66%; 95% CI: 56–73) during 12 months of follow-up after the third dose” WHO guidelines for malaria, 2026, p. 158. See also WHO, Malaria vaccine position paper, May 2024.
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“The incremental efficacy provided by the booster dose during the 12 months after booster vaccination was 25·6% (95% CI 18·2–32·3; table 1 and appendix p 30).” RTS,S Clinical Trials Partnership 2015, p. 7. (This figure is for children aged 5–17 months at first vaccination.)
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- “The protective efficacy of the combination as compared with chemoprevention alone was 62.8% (95% CI, 58.4 to 66.8) against clinical malaria…” Chandramohan et al. 2021 (3-year results), p. 1005.
- “This was a double-blind, individually randomised, controlled, non-inferiority and superiority, phase 3 trial done at two sites: the Bougouni district and neighbouring areas in Mali and Houndé district, Burkina Faso. … The combination of RTS,S/AS01E and SMC was superior to SMC (protective efficacy 57·7%, 95% CI 53·3 to 61·7) and to RTS,S/AS01E (protective efficacy 59·0%, 54·7 to 62·8) in preventing clinical malaria. RTS,S/AS01E was non-inferior to SMC (hazard ratio 1·03 [95% CI 0·95 to 1·12]).” Dicko et al. 2024 (5-year extension of the same trial), p. 75.
- 27
“The primary outcome of this impact evaluation was mortality due to any cause, except injury, in children eligible to receive three doses of RTS,S. … The mortality rate ratio was 0·87 (95% CI 0·77-0·97; p=0·016).” Mwapasa et al. 2026, p. 1796.
- 28
See this section of our interim report on iCCM, including its footnote 6.
- 29
WHO, Global Technical Strategy for Malaria 2016-2030, p. 15.
- 30
We published an interim review of iCCM in 2016.
- 31
National treatment policies in every country in the WHO African Region use artemether-lumefantrine, artesunate-amodiaquine, or another ACT to treat confirmed uncomplicated P. falciparum malaria. See World Health Organization, World malaria report 2025, Annex 4-B, p. 184.
- 32
- “We estimate the PE of ACT treatment of uncomplicated P. falciparum malaria on reducing malaria mortality in children 1–23 months to be 99% (range: 94-100%)”. Thwing, Eisele, and Steketee 2011, p. 1.
- "Artemisinin combination therapies (ACT) are highly effective for preventing an uncomplicated P. falciparum malaria fever from progressing to severe disease, which can result in death [3,4]." Thwing, Eisele, and Steketee 2011, Background.
- 33
See the evidence section of our interim intervention report on iCCM for our review of these two RCTs.
- 34
The clearest evidence for more intense implementation comes from a single program in Uganda that was evaluated twice. As a pilot, it reduced under-5 mortality by 27% (Björkman Nyqvist et al. 2019, abstract). However, over five years of national scale-up Awor et al. 2025 found no significant effect. This scale-up was run by two implementers; midway through, one of these implementers raised CHWs’ monthly pay, increased CHW numbers, and introduced data-driven supervision. Mortality fell 28% for that implementer, and was unchanged for the other (Awor et al. 2025, pp. 11-12). This suggests that more intensive implementation may improve results, but the picture is not clear-cut. First, the two implementers differed in delivery model, so the difference may not be due to implementation intensity. Second, evidence from Mali suggests that more intensity does not reliably reduce mortality. There, a trial compared iCCM with and without proactive home visits and found no difference in child mortality (though both arms were fairly intensive) (Liu et al. 2024, p. 1).
- 35
“Spatial emanators – also known as spatial repellents – emit active ingredients into the air to kill mosquitoes, deter them from entering treated spaces, and prevent them from locating and biting human hosts”. WHO, "WHO recommends spatial emanators for malaria vector control and prequalifies first two products," August 13, 2025.
- 36
- “Unlike ITNs, spatial emanators may provide an added layer of protection against day-time mosquito biting, when residents of a household are active within the home and not sleeping under a net.” WHO, "WHO recommends spatial emanators for malaria vector control and prequalifies first two products," August 13, 2025.
- “They are easy to use: Deployment of spatial emanators requires minimal user effort (compared to ITNs) and minimal training for deployment (compared to IRS)." WHO guidelines for malaria (10 September 2026 version), p. 76.
- 37
- "The products emit the active ingredient transfluthrin." WHO, "WHO recommends spatial emanators for malaria vector control and prequalifies first two products," 2025.
- "ITNs that are prequalified by WHO, which in many settings continue to be pyrethroid-only long-lasting insecticidal nets (LLINs)..." WHO, WHO guidelines for malaria, 2026, p. 36.
- 38
“WHO has issued a conditional recommendation in support of the use of spatial emanators indoors in addition to ITNs”. WHO, "WHO recommends spatial emanators for malaria vector control and prequalifies first two products," August 13, 2025.
- 39
“WHO has also prequalified two spatial emanators products, Mosquito Shield and Guardian, manufactured by SC Johnson & Son, Inc. … The products have been shown to remain effective for up to 1-month and 12-months, respectively”. WHO, "WHO recommends spatial emanators for malaria vector control and prequalifies first two products," August 13, 2025.
- 40
“The Global Fund to Fight AIDS, Tuberculosis and Malaria (the Global Fund), in partnership with the United States government and SC Johnson... will support the deployment of SC Johnson Guardian™. ... the partners aim to protect at least 60 million people by 2028.” Global Fund, "Global Fund and United States partner to accelerate rollout of innovative malaria prevention tool," May 13, 2026.
- 41
“spatial repellents significantly reduced the hazard rate of first-time malaria infection by 33·4% (95% CI 11·1-50·1; p=0·0058) and the hazard rate of overall new malaria infections by 32·1% (15·9-45·2; p=0·0004). … Our trial provides the first evidence of a demonstrative spatial repellent protective efficacy in reducing risk of malaria infection in an African setting characterised by high malaria transmission, pyrethroid resistant malaria vectors, and high coverage of insecticide treated nets” Ochomo et al. 2025, p. 147.
- 42
“The estimated PE of SRs against the first-time malaria infection relative to placebo was -3.10% (95% 2-sided CI -32.24%, 19.62%, p-value 0.810).” Sagara et al. 2025, Abstract.
- 43
"Indoor residual spraying (IRS) involves applying residual insecticide to potential vector resting sites ... on the interior surfaces of human dwellings or other buildings." "The main aim of IRS is to kill vectors before they are able to transmit pathogens to humans." WHO, 2024 operational manual on IRS, overview.
- 44
"Access to effective vector control using ITNs or IRS at optimal coverage levels should be ensured for all populations at risk of malaria in most epidemiological and ecological settings." World Health Organization, WHO guidelines for malaria, 2026, p. 74.
- 45
"The co-deployment of ITNs and IRS is not recommended for prevention and control of malaria in children and adults in areas with ongoing malaria transmission. Priority should be given to delivering either ITNs or IRS at optimal coverage and to a high standard, rather than introducing the second intervention as a means to compensate for deficiencies in the implementation of the first intervention." WHO, WHO guidelines for malaria, 2026, p. 72.
- 46
Malaria incidence fell by 79.3% in IRS areas and by 24.3% in nets-only control areas. That means IRS areas ended at 20.7% of their starting incidence, whereas control areas ended at 75.7% of their starting incidence. 20.7% is about 27% of 75.7%, so IRS areas ended with about 73% lower incidence than control areas. The paper’s adjusted incidence rate ratio is 0.27, 95% CI 0.22 to 0.34.
- 47
Chabi et al. 2026 is a quasi-experimental study of IRS withdrawal in Sakassou, Côte d’Ivoire. Its case analysis (an interrupted time series) found incidence roughly doubled after IRS stopped, before Interceptor G2 nets arrived. “IRS withdrawal was associated with an immediate and substantially sharp upward step in both the fitted line and observed data in November 2022 after the last round of IRS, with the number of cases and incidence rising from approximately 20 to over 45 per 1000 population within 2 months (IRR = 1.78; P < 0.001).”
- 48
"Combining indoor residual spraying with pirimiphos-methyl and PBO long-lasting insecticidal nets provided no additional benefit compared with PBO long-lasting insecticidal nets alone” Protopopoff et al. 2018, p. 1577.
- 49
In a cluster-randomized trial in 39 villages in Burkina Faso and Côte d'Ivoire, adding pirimiphos-methyl IRS to standard nets reduced malaria incidence by 23% compared with nets alone. "During the post-intervention period, passive case detection showed a 23% reduction in malaria incidence rate (rate ratio 0·77 [95% CI 0·64-0·93], p=0·0073) in the LLIN plus IRS group ... compared with the LLIN-alone (control) group." Moiroux et al. 2025, p. e1605.
- 50
"Overall, the addition of IRS reduced malaria parasite prevalence (RR 0.61, 95% CI 0.42 to 0.88; 4 cRCTs, 16,394 participants; high-certainty evidence). IRS may also reduce malaria incidence on average (rate ratio 0.86, 95% CI 0.61 to 1.23; 4 cRCTs, 323,631 child-years; low-certainty evidence) but the effect was absent in two studies." Pryce, Medley, and Choi, 2022, abstract, p. 2.
- 51
The study in Tororo, Uganda, compared malaria transmission before and after universal net distributions and repeated rounds of IRS with bendiocarb and then pirimiphos-methyl. It had no control site. "Consequently, the aPfEIR dropped from 129 to 0 infective bites per person per year (p < 0.001) following vector control." Musiime et al. 2019, p. 4.
- 52
"A dramatic resurgence of malaria in Tororo was temporally associated with a change to clothianidin-based IRS formulations." Kamya et al. 2024. See also Epstein et al. 2022.
- 53
"After the third spray round, no infective mosquitoes were identified." Sharp et al. 2007, abstract.
- 54
"[T]he impact of IRS may vary in different settings depending on a number of factors, such as the behaviour of the mosquito species, the level and mechanism(s) of insecticide resistance in vectors, parasite prevalence, and coverage of IRS in the population. As with deploying IRS in more stable settings, IRS will only be effective where vectors rest primarily indoors and mosquitoes are susceptible to the insecticide being deployed." WHO, WHO guidelines for malaria, 2026, p. 72.
- 55
IRS costs more per person protected than nets. A systematic review of costs from 2005 to 2018 found median costs of US$5.70 per person protected per year for IRS and US$1.39 for nets. WHO, WHO guidelines for malaria, 2026, pp. 59 and 71, citing Conteh et al. 2021.
- 56
In northern Uganda, malaria cases rose significantly within 10 months of IRS stopping. "Withdrawing IRS after 5 years of sustained use in three districts in northern Uganda was associated with a more than fivefold increase in malaria cases within 10 months." Namuganga et al. 2021, Discussion.
- 57
We commissioned a consultant to assess absorptive capacity, including how supply chain constraints could limit new programs. Consultant, "Absorptive capacity scoping" memo for GiveWell, July 5, 2026. (unpublished).
- 58
See GiveWell, "CHAI - Malaria RDT Emergency Procurement in Nigeria (July 2025).” We have also made the following grants for which we have not yet published grant pages:
- Procurement of Artemisinin-Based Combination Therapies for Malaria, grant to CHAI, Sept 2025
- Procurement of Malaria Rapid Diagnostic Tests, grant to CHAI, Oct 2025
- Procurement of Injectable Artesunate, grant to PATH, Aug 2025
- 59
For example, we discussed supply chain constraints and possible interventions with CHAI. GiveWell, call with CHAI, August 2026 (unpublished).