In a nutshell
In March 2025, GiveWell recommended a grant of $408,142 to Malaria Consortium to support additional monitoring and evaluation (M&E) for the 2025 insecticide-treated net (ITN) campaign in Ondo state, Nigeria. The grant will fund two specific M&E components: incidence monitoring and physical durability monitoring. We expect these activities to run from 2025-2028. (More)
We recommended funding these two components due to:
- Decision-relevance - The results from both monitoring components can directly inform our cost-effectiveness model, which can help us make better funding decisions. Incidence data will help us understand the real-world impact of ITN campaigns on malaria cases, while physical durability data will improve our understanding of how long nets remain physically intact in the field. (More)
- Longitudinal value - There is particular value in continuing incidence monitoring in Ondo, where data collection has been ongoing since 2018, as this allows us to observe longer-term trends in malaria cases before and after multiple ITN campaigns. (More)
- Relatively low cost - Both components are relatively light-touch additions to existing activities. (More)
Our main reservations about this grant are:
- No previous results available - At the time we made this grant, we hadn't yet seen results from the previous round of incidence or physical durability monitoring that we funded in Ondo in 2021 (see webpage for that grant), which makes it difficult to fully assess the value of continued monitoring. We expected to receive preliminary incidence and durability results in April 2025. (More)
- Component selection - We chose to fund only a subset of the monitoring components Malaria Consortium proposed to us. Given our limited investigation time and expertise in this area, we may not have chosen to fund the right components. (More)
- Whether Malaria Consortium is best placed to conduct this monitoring - While we have confidence in Malaria Consortium as an implementer, we are less familiar with their research capabilities. GiveWell is also considering moving towards third-party monitoring to reduce bias. (More)
Published: July 2026
1. Background
We believe that distributing insecticide-treated nets (ITNs) is one of the most cost-effective programs that donors can support. We've estimated their mass distribution to be between 9x and 23x as cost-effective as our benchmark across the locations where we've supported distribution campaigns.1
In August 2024, we made a grant to Malaria Consortium to implement an ITN campaign in Ondo, Nigeria in 2025. This was a renewal of a previous grant we made to Malaria Consortium for ITN campaigns in Ondo and Anambra, Nigeria in 2021. Shortly after making the 2021 grant, we funded additional M&E in Ondo to support the following M&E components: malaria incidence trend analysis, tests of local mosquitoes' susceptibility to insecticide used in ITNs, net durability monitoring, tracking exposure to infected mosquitoes, surveys to track the number of nets in each household and reported use rates, full cost accounting, and meteorological tracking.2
The President's Malaria Initiative (PMI), historically part of the U.S. Agency for International Development (USAID), has previously invested in similar monitoring activities in Nigeria, including incidence trends, durability monitoring, and entomological surveillance in various states.3 However, due to USAID funding cuts, our understanding is that PMI is likely to reduce its scope to focus only on activities that are directly life-saving.4 This would mean that these M&E activities may no longer be funded by PMI, creating potential gaps in important monitoring data.
2. What we think this grant will do
This grant will fund two specific M&E components associated with the 2025 ITN campaign in Ondo state, Nigeria: incidence monitoring and physical durability monitoring.
2.1 Incidence monitoring
Malaria Consortium will collect patient-level data on malaria cases from public health facilities.5 This will involve extracting data from the existing patient registers maintained by health facility staff, recording it in a standardized template, and submitting it to supervisors on a weekly basis.6
We estimate that the incidence monitoring component of this grant will cost $265,811 (65% of the overall grant) for monitoring from 2025-2028.7 This will allow us to observe malaria incidence trends before and after both the 2021 and 2025 ITN campaigns, as our previous grant covered this monitoring from 2018 to 2024.
2.2 Physical durability monitoring
Once a year for three years, during annual household surveys (which were already funded as part of the main campaign grant), Malaria Consortium staff will visit households to measure what proportion of nets are still in place and the extent of physical damage to nets (number and size of holes).8 The household survey will also include questions about the physical damage to nets, such as how holes developed and whether the household has attempted to repair them.
We estimate that the physical durability monitoring component of the grant will cost $142,331 (35% of the overall grant).9 While we funded durability monitoring as part of our previous grant, this was previously conducted as a standalone survey as we did not fund annual household surveys for the 2021 campaign. We believe that integrating physical durability monitoring with the household surveys will provide decision-relevant information while being lower-cost than conducting these two surveys separately.
3. Why we made this grant
3.1 Decision-relevance
Incidence monitoring can help inform outcome-related CEA parameters
Monitoring incidence trends over time can give us insight into the effectiveness of ITN campaigns and inform whether we should continue funding campaigns in Ondo.
If we don't observe the expected decrease in malaria incidence from before to after an ITN distribution, we may adjust CEA parameters related to incidence accordingly.10 We could also investigate why we're not observing the expected decrease using household survey data and other sources. Depending on what we find (e.g. more unaccounted-for nets than expected, lower than expected net use), we may adjust other CEA parameters related to these factors. This analysis could ultimately lead us to stop funding net campaigns in Ondo if we don't believe they're having their intended impact.
Additionally, we heard from some stakeholders that incidence monitoring data could support domestic advocacy efforts for state contributions to ITN campaigns.11 While we're not placing substantial weight on this possibility, we consider this to be a secondary benefit of this monitoring.
Physical durability monitoring will help refine our understanding of net lifespan
We can use the results from physical durability monitoring to update our analysis of ITN durability, which feeds into our cost-effectiveness model. Our analysis of physical ITN durability includes key parameters such as the percentage of nets in good condition, nets in serviceable condition, and nets too torn to be useful.12 We think we would use the results of this monitoring to update our analysis unless there were serious data quality issues, as we expect that the monitoring data would directly map onto the parameters we use in our analysis.
We currently think that ITN durability is a significant weakness in our cost-effectiveness model because we have limited data in this domain, particularly Nigeria-specific data and data on dual active ingredient (dual AI) nets.13 Given that we've directed a significant proportion of funding for ITN campaigns to Nigeria in recent years,14 we think it's particularly important to develop a good understanding of net durability in the Nigerian context.
While the 2021 ITN campaign used pyrethroid-piperonyl butoxide (PBO) nets, the 2025 ITN campaign will use pyrethroid-chlorfenapyr nets - a type of dual AI net. As the global trend appears to be moving toward dual AI nets, we think it will become increasingly important to have data on their durability. According to the Alliance for Malaria Prevention (AMP)’s Net Mapping Project, in 2024, 47% of ITNs produced globally were dual AI as compared to just 2% in 2019.15
3.2 There is greater value to collecting incidence data in Ondo vs other states
We think there is greater value to continuing to collect incidence data in Ondo as compared to other states in Nigeria where we may fund ITN campaigns in the future for several reasons:
- There is a longitudinal benefit to incidence tracking. All else being equal, it's more useful to observe how incidence has changed over a longer time horizon in one location rather than splitting observations across multiple contexts. Data points across time in one location can show how malaria burden is changing in that specific context.
- We think it's likely to be logistically simpler and cheaper for Malaria Consortium to continue incidence monitoring in a location where they've already set up this infrastructure versus setting it up in a new location. Malaria Consortium's budgets reflect this - the total budget for incidence monitoring in 2021 was approximately $580,000, compared to approximately $266,000 in 2025.16 However, several other factors could be contributing to this cost difference, including the devaluation of the Nigerian naira in 2023-2024,17 and the fact that this grant covers four years of monitoring (2025-2028) whereas the previous grant covered seven years (2018-2024). We did not deeply investigate the reasons for the cost difference between 2021 and 2025.
3.3 These monitoring components are relatively low-cost
Incidence monitoring
As described above, incidence monitoring involves Malaria Consortium staff compiling patient-level data from health facilities' outpatient registers in a standardized template. Since the raw data has already been collected by health facilities, we think that compiling this data in Malaria Consortium's template is relatively simple and light-touch and therefore low-cost.
Physical durability monitoring
Physical durability monitoring will be conducted at the same time as the annual household surveys, which we already funded as part of the campaign implementation grant. This is a shift from the durability monitoring we funded in 2021, which used a cohort sample whereby specific nets were tagged during distribution and assessed 12, 24, and 36 months after distribution.
After discussing this with Malaria Consortium, we agreed that changing the sample for the physical durability monitoring to match that of the annual household surveys would still give us valid, decision-relevant data while being lower cost than the cohort method because both studies would be conducted concurrently. The sample size for physical durability monitoring will be campaign nets found in approximately 624 households during each survey round (52 clusters, 12 households per cluster)18 , which we think is adequate based on PMI's guidance and the sample sizes of studies we already use in our analysis of ITN durability.
The disadvantage of this change in methodology is that we would no longer have historical data on individual nets. However, this is not a high-priority question for us and we don’t think this data would be useful to update our cost-effectiveness model.
4. Risks and reservations
4.1 We haven't seen results from the previous monitoring we funded in Ondo or Anambra
We previously funded durability monitoring (physical and chemical) in both Ondo and Anambra in 2021 and incidence monitoring in Ondo only, but at the time we made this grant, we had not yet seen any durability results for any time point (12-, 24-, or 36-month) from either state or any incidence results. We had initially expected to receive the 12-month durability reports in August-September 2024 and the 24-month reports in October-November 2024.
When we asked Malaria Consortium about these timelines, they explained that they would not be sharing any results until after all data collection and analysis was complete because they believed the results would only be interpretable after 36 months;19 after further discussion, they agreed to share interim results earlier.20 For the incidence results, Malaria Consortium told us that they have completed compiling and digitizing data up to March 2024 and that they will be able to share preliminary incidence results in April 2025.21
Not having seen any results from the previous rounds of incidence or durability monitoring is a concern for two reasons:
- Not knowing exactly what the results look like and which parameters will be included means that we cannot be certain how useful the results will be in informing our cost-effectiveness model.
- The delay in sharing interim results could potentially indicate issues with data collection that we do not yet know about. If substantive problems exist, we might want to reconsider funding additional monitoring or request specific methodological changes for future rounds.
4.2 Uncertainty about our choice of M&E components
Malaria Consortium originally proposed the following M&E components for this grant: incidence monitoring, durability monitoring (which we disaggregated into physical durability and chemical durability), and entomological monitoring (which we disaggregated into insecticide resistance monitoring and monitoring of mosquito biting behavior and sporozoite infection rates).22 After completing our grant investigation, we decided to fund only the incidence and physical durability monitoring components.
We identified several reasons for not funding the other three components:
- Chemical durability monitoring: Our current model of insecticide loss does not rely on monitoring data as an input due to our uncertainty about the relationship between insecticide content and effectiveness. Therefore, we do not anticipate that monitoring data would significantly change our assumptions or decision-making.
- Insecticide resistance monitoring: We are uncertain about the relationship between bioassay results and net effectiveness, whether bioassays are sufficient to test insecticide resistance, and the external validity of these results outside of Ondo and the surrounding area.
- Biting behavior and sporozoite infection rates: We are uncertain as to how we would use these results to inform our cost-effectiveness model. We are also concerned that the low mosquito sample size observed at baseline during the last monitoring round we funded in Ondo may be repeated in a future round, which would make it difficult to draw conclusions with confidence.23
However, we acknowledge that our investigation of these components was conducted in a limited timeframe and that our team does not have specialized expertise in all aspects of mosquito entomology or vector control research, so it’s possible that we made the wrong decisions. This is compounded by our belief that PMI (historically a major funder of such monitoring) is likely to reduce its monitoring activities due to a shift towards activities that are directly life-saving. This could make some of the components we chose not to fund more valuable than we initially assessed if these data gaps are not filled by other actors.
4.3 We are uncertain about whether Malaria Consortium is the right organization to conduct this monitoring
Given that Malaria Consortium’s seasonal malaria chemoprevention (SMC) program is one of GiveWell’s top charities, we have high confidence in the organization as an implementer, particularly for SMC, and most of our grants to Malaria Consortium have gone towards direct implementation of malaria prevention programs.24 We are less familiar with, and less confident in, Malaria Consortium’s capabilities as a research organization. We have also funded very little malaria-related monitoring or research with other organizations.25 Therefore, we are uncertain about whether Malaria Consortium is the right organization to be conducting this monitoring; it seems plausible that there could be other organizations in Nigeria that are equally or better placed to do this. We did not look into the possibility of funding other research organizations in Nigeria as part of this investigation.
Furthermore, GiveWell is beginning to think about the value of third-party monitoring across all grantees as we believe this could reduce bias in monitoring results. We may consider funding another research organization to conduct monitoring of a future Malaria Consortium ITN or SMC campaign.
5. Plans for follow up
We will follow up on this grant through bi-monthly calls with Malaria Consortium throughout the campaign planning, implementation, and post-campaign evaluation phase, and biannual calls thereafter.
We will review M&E reports shared by Malaria Consortium (from both the previous round and this round), paying particular attention to:
- Methodological quality and completeness of data collection
- How the findings compare to our expectations
- Whether the data appears reliable enough to inform updates to our cost-effectiveness model
Once we receive the incidence and physical durability results, we may make suggestions for improvement to Malaria Consortium for the monitoring components funded by this grant to try to ensure that the results from subsequent rounds are as valuable as possible.
We will update our cost-effectiveness model and relevant analyses based on the findings as appropriate.
6. Internal forecasts
For this grant, we are recording the following forecasts:
| Confidence | Prediction | By time | Resolution |
|---|---|---|---|
| 80% | We use last round's physical durability results in our analysis of ITN durability | January 2026 | |
| 50% | We use last round's incidence results to update our cost-effectiveness model in some way | May 2025 | |
| 80% | We use this round's physical durability results in our analysis of ITN durability | January 2029 | |
| 60% | We use this round's incidence results to update our cost-effectiveness model in some way | January 2029 | |
| 45% | We will fund Malaria Consortium for at least one of these monitoring components again in Ondo (by 2028) | December 2027 | |
| 45% | GiveWell will fund other entomological surveillance (outside of Ondo) by June 2026 | June 2026 | |
| 45% | GiveWell will fund other net durability studies (outside of Ondo) by June 2026 | June 2026 |
7. Our process
- We had two conversations with Malaria Consortium specifically about this grant and asked a number of questions over email.
- We reviewed materials shared by Malaria Consortium from the previous round of monitoring.
- We had internal conversations with several GiveWell staff members about the specific monitoring components and impressions of Malaria Consortium broadly.
- We conducted shallow literature scans to get a sense of typical sample sizes for entomological studies, existing incidence, durability, and entomology monitoring in Nigeria, and bioefficacy durability for PermaNet Dual nets (the type of net that will be used for the 2025 Ondo mass campaign).
Sources
- 1
- For more on our evaluation of the mass distribution of insecticide-treated nets, see our intervention report.
- Prior to November 2025, we used a benchmark that we described as multiples of “cash.” While we’ve changed how we calculate our benchmark, the value of that benchmark remains similar, which means cost-effectiveness estimates remain comparable across the old and new approaches. Read about our benchmark for comparing different programs here.
- 2For the 2025 campaign (August 2024 grant), we included funds for annual household surveys to track net retention and use, among other parameters.
- 3See more information about PMI’s M&E activities on ITN durability in Nigeria here and entomological monitoring here.
- 4We have learned through our conversations with PMI implementing partners and statements from the U.S. State Department (such as this waiver) that future U.S. foreign assistance is likely to focus on life-saving activities. GiveWell in conversation with PMI implementing partners. (unpublished)
- 5
- “... [C]ollect data on malaria cases seen at selected health facilities in order to study changes in incidence rates after the campaign compared to a baseline period. Thirty-two primary health centres selected from various wards across the state will be used as sentinel sites to compile malaria data from outpatient registers” Malaria Consortium, “Standard operating procedure for malaria outpatient data compilation,” September 15, 2022.
- Our understanding is that the next round of incidence monitoring will follow the same methodology as outlined in the above SOP, with the one exception being that data will be collected from 31 health facilities, not 32. GiveWell in conversation with Malaria Consortium, October 16, 2024. (unpublished). We did not ask MC about this discrepancy.
- 6"Compile data on all outpatients seen at the health facility using form FRM-INC1...Hand over compiled data to the health facility supervisor weekly." Malaria Consortium, “Standard operating procedure for malaria outpatient data compilation,” September 15, 2022.
- 7Malaria Consortium’s budget includes $265,811 for incidence monitoring. This figure is calculated in an unpublished outdated version of the program budget.
- 8Our understanding is that the next round of physical durability monitoring will use the same sample for the annual household surveys as opposed to a cohort. The previous round of physical durability monitoring used a cohort sample, whereby a cohort of nets are tagged during distribution and assessed 12, 24, and 36 months after distribution. If we continued the durability monitoring using the same methodology, the sample would be different from that of the annual household surveys, which uses a different random sample of all households who received nets at each time point. After discussing this with Malaria Consortium, we agreed that changing the sample for the physical durability monitoring to match that of the annual household surveys would still give us valid, decision-relevant data for a lower cost than using a cohort sample. Malaria Consortium in correspondence to GiveWell, March 21, 2025. (unpublished)
- 9See Malaria Consortium’s budget. The total grant cost is $408,142, with $265,811 for incidence monitoring, and the remainder for physical durability monitoring ($408,142-$265,811=$142,331). These figures are calculated in an unpublished outdated version of the program budget.
- 10This could potentially involve adjusting the external validity adjustment to the reduction in malaria incidence found in the Pryce et al meta-analysis or implementing stand-alone ad hoc adjustment.
- 11GiveWell in conversation with stakeholders. (unpublished)
- 12See this sheet of our analysis of ITN durability.
- 13Our current modeling of physical durability in Nigeria is based on just one study conducted by PMI in 2019. Of the 39 studies we use in our analysis of physical durability, only 6 of them were conducted on dual AI nets. Dual AI nets combine two different types of insecticide to address resistance that mosquitoes may have developed to single-insecticide nets.
- 14See this table for a list of our recent grants supporting ITN distributions, including grants to support ITN distributions in Nigeria in 2022 and 2023.
- 15These reports are available here. These figures are pulled from the 2024 and 2019 rows of the ‘Global by Type’ tab in the ‘2024 Q4 Net Mapping Project report’ file.
- 16See our budget breakdown in this section of our page on the previous grant, and the section above for the breakdown for this grant.
- 17The devaluation of the Naira is described further Reuters, “Nigeria's latest devaluation may be 'turning point' in currency reform drive,” February 5, 2024.
- 18 Malaria Consortium in correspondence to GiveWell, March 15, 2026. (unpublished)
- 19GiveWell in conversation with Malaria Consortium, Jan 8, 2025. (unpublished)
- 20We received an interim durability monitoring report for the period from baseline to 24 months after the campaign in May 2025. (unpublished)
- 21We received preliminary incidence results in May 2025. (unpublished)
- 22GiveWell in conversation with Malaria Consortium, Aug 14, 2025. (unpublished)
- 23Malaria Consortium, “Results of baseline entomological surveys, Monitoring and Evaluation of ITN Campaigns in Ondo and Anambra States,” March 2023. (unpublished)
- 24Of the 40 grants ($549,798,395) made to Malaria Consortium since 2017, only 3 ($3,659,803) have been dedicated M&E grants. Other implementation grants include M&E components, which constitute a smaller share of total grant value than direct implementation efforts.
- 25Since 2014, we have only made four grants to organizations other than Malaria Consortium (IDinsight 2018, IDinsight 2024, PSI 2025, and a forthcoming PSI grant) for dedicated malaria monitoring or monitoring support. These grants are valued at approximately $795,000, out of approximately $913 million directed towards all malaria programming in the same time period.