In low- and middle-income countries, household floors made of soil remain common. Concrete floors are desirable household upgrades because they offer durability, improved hygiene, and flood resilience, and their prevalence is increasing. However, cement production is a substantial contributor to global anthropogenic carbon dioxide emissions. This study assessed the acceptability and feasibility of sustainable cement-based floors with lower embodied carbon; these floors replaced 20% of cement with fly ash, a byproduct of coal combustion. To assess whether low carbon cement floors are as acceptable as traditional cement-based floors, in-depth interviews were conducted with 30 respondents from 20 households in rural Bangladesh in which soil floors were replaced with either low carbon cement or traditional cement-based floors. Findings revealed that both flooring types were highly accepted due to ease of cleaning, health benefits, and protection from environmental hazards. Traditional cement floors were preferred in terms of repair and maintenance as the users were concerned about the availability of fly ash and concrete blocks in rural settings. Financial constraints emerged as a major barrier to cement-based floor adoption for both traditional and lower embodied carbon cement-based floors, with most respondents prioritizing roof and wall improvements over flooring. Subsidized housing programs were seen as a crucial enabler for cement-based floor installation, as self-financing was largely considered unattainable. This study demonstrates that in a rural, low-income population Bangladesh, cement-based floors with lower embodied carbon were as acceptable as traditional cement-based floors, but installation of either type of floor may require government subsidies.

Introduction:Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) has become less effective at preventing malaria due to rising parasite resistance. IPTp with dihydroartemisinin-piperaquine (DP) alone or in combination with SP (DP+SP) dramatically lowers the risk of malaria in pregnancy compared to SP but is associated with lower birthweight and early life wasting. We estimated the effect of IPTp-DP, DP+SP, and SP on infant growth outcomes and assessed possible treatment mechanisms through a causal mediation analysis. Methods:We used infant follow-up data (N=761) from a trial (NCT04336189) that randomized pregnant women to receive monthly IPTp-DP, SP, or DP+SP. We compared weight-for-length (WLZ) and length-for-age (LAZ) z-scores between treatment arms. We assessed possible mediation through pregnancy, birth, and infancy factors using interventional indirect effect models. Results:Compared to IPTp-SP, IPTp-DP+SP decreased mean WLZ by 0.18 [95% confidence interval (CI) -0.03, 0.39] between 1-3 months and 0.28 (95% CI 0.07, 0.49) between 4-6 months, with the largest differences among primigravidae. Lower risk of active placental malaria in IPTp-DP+SP helped reduce differences in mean WLZ vs IPTp-SP (+0.06, 95% CI 0.02, 0.10). The IPTp-DP+SP arm had up to 0.28 lower mean LAZ between 7-13 months compared to IPTp-DP, particularly among children who were wasted between 0-6 months; low birthweight had a persistent, mediating effect on linear growth. Conclusion:Adverse birth outcomes contributed to early growth faltering among children born to mothers receiving IPTp-DP+SP vs IPTp-SP, but the prevention of placental malaria partially counteracted the negative effects of IPTp-DP+SP on ponderal growth.

There is limited evidence regarding the association between weather and Plasmodium vivax (Pv), particulary in Latin America where Pv is the predominant malaria species and key challenge for countries to achieve malaria elimination. We analyzed the association between weather and Pv malaria incidence from 2017 to 2024 in 136 communities in the Peruvian Amazon. Monthly community-level incidence was calculated using Pv case data from Notiweb, the national epidemiological surveillance system, and population census data. Predictors included weekly minimum and maximum temperature and total weekly precipitation and were calculated using hourly weather from the climate dataset ERA5. Non-linear distributed lag models were fit using a lookback period of 2–16 weeks. Temperature models were adjusted for total precipitation; precipitation models were adjusted for maximum temperature. Sub-group analyses were conducted by community type (adjacent to river versus highway) and El Niño Southern Oscillation (ENSO) period. Minimum temperature at the 90th percentile (23.7°C) was associated with 10

BACKGROUND:Intermittent preventive treatment in pregnancy (IPTp) with dihydroartemisinin-piperaquine (IPTp-DP) is more effective than sulfadoxine-pyrimethamine (IPTp-SP) at reducing the burden of malaria in pregnancy in settings with high SP resistance. Paradoxically, IPTp-DP has been associated with lower birth weights compared with IPTp-SP. Whether the impacts of IPTp-DP extend after birth is unknown. METHODS:We conducted a double-blind randomized controlled trial to compare malaria burden and growth among infants born to mothers who were randomized to monthly IPTp-SP, IPTp-DP, or IPTp-DP+SP. Infants were followed to 12 months of age by passive and active surveillance. The primary outcome was clinical malaria incidence; secondary outcomes included parasite prevalence by microscopy or quantitative PCR, and infant growth outcomes. RESULTS:Among 871 infants enrolled, there were 667 episodes of clinical malaria. Compared to infants whose mothers received IPTp-SP, malaria incidence was similar in infants whose mothers received IPTp-DP (incidence rate ratio [IRR] 1.04, 95% confidence interval (CI) 0.78-1.38) or IPTp-DP+SP (IRR=0.93, 95% CI 0.68-1.26). Overall parasite prevalence at monthly visits was 21.8%. Parasite prevalence was also similar between groups. The prevalence of wasting at birth was higher in infants whose mothers received IPTp-DP+SP (PR= 2.30, 95% CI 1.07, 4.97) or IPTp-DP (RR= 2.25, 95% CI 1.03, 4.94) than those that received IPTp-SP, but differences between groups resolved by 3-6 months of age. CONCLUSION:There were no significant differences in infant outcomes between the three IPTp arms apart from a transiently increased risk of wasting among infants born to mothers who received DP-containing IPTp regimens.

BACKGROUND:In sub-Saharan Africa, sexually transmitted and reproductive tract infections (STIs/RTIs) are important but underdiagnosed risk factors for adverse pregnancy outcomes. Sulfadoxine-pyrimethamine (SP), used for the intermittent preventive treatment of malaria in pregnancy (IPTp), may reduce the STI/RTI burden due to its antimicrobial activity. We assessed the impact of IPTp regimens on STI/RTI prevalence and evaluated associations between STIs/RTIs and adverse birth outcomes. METHODS:We conducted a secondary analysis of a randomized-controlled trial comparing monthly IPTp with SP, dihydroartemisinin-piperaquine (DP), or DP+SP among pregnant women in Uganda. Vaginal swabs collected at or near delivery were tested for Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Group B Streptococcus (GBS) by using GeneXpert; bacterial vaginosis was assessed by using Nugent scoring. Log-binomial regression was used to compare STI/RTI prevalence between IPTp arms; IPTp-DP served as the reference arm. Multivariable Poisson regression with robust standard errors was used to evaluate associations between infections and preterm delivery, term low birthweight (LBW), overall LBW, and small-for-gestational age. RESULTS:Among the 2265 participants assessed, the IPTp-SP arm had an 80% [95% confidence interval (CI): 67%-88%] lower prevalence of C. trachomatis (2.5% vs 12.4%) and a 35% (95% CI: 1%-57%) lower prevalence of GBS (7.7% vs 11.7%) at delivery compared with the IPTp-DP arm. Chlamydia trachomatis was associated with increased preterm delivery [prevalence ratio (PR) = 1.86, 95% CI: 1.07-3.25] and GBS was associated with increased term LBW (PR = 2.08, 95% CI: 1.06-4.08). CONCLUSION:Monthly IPTp-SP may reduce the risk of adverse birth outcomes through its activity against C. trachomatis and GBS, highlighting its potential non-malarial benefits.

In low-income countries, ESBL-producing Escherichia coli (ESBL-EC) is frequently detected in humans, animals and household environments, indicating widespread exposure to antimicrobial resistance (AMR). Established risk factors such as antibiotic use do not explain the high community carriage of AMR in all settings; identifying the dominant exposure pathways can inform interventions against AMR. We aimed to investigate (i) animal-human-environment sharing of AMR by assessing associations between the abundance of ESBL-EC in the household environment, domestic animal feces and young children's stool and (ii) household factors associated with ESBL-EC abundance in these reservoirs. We enrolled 112 households from the CRADLE trial in rural Bangladesh. We enumerated ESBL-EC in drinking water, food, child hand rinses, outdoor soil, indoor floor swabs, chicken and cow feces, and stool from children aged 6 months. We recorded indicators of sanitation, animal ownership/management, human and animal antibiotic use, and child exposure behaviors using structured questionnaires and spot checks. The highest prevalence of ESBL-EC was in child stool (95.6%) and animal feces (82.3-96.9%), followed by soil (48.2%) and floors (36.6%); < 10% of food, child hands and drinking water harbored ESBL-EC. The abundance of ESBL-EC in child stool was not associated with its abundance in any sampled matrix; the abundance in chicken but not cow feces showed positive correlations with soil, floors, child hands, and drinking water (correlation coefficients: 0.19-0.39, p-values < 0.05). Higher-quality latrines (improved, pour-flush, with slab) were associated with lower ESBL-EC abundance across matrices; unsafe animal management (animals roaming or spending the night inside the home) was associated with higher abundance. Child antibiotic use and exposure behaviors (soil ingestion, time spent on floor) were not associated with ESBL-EC abundance in child stool. We observed high AMR colonization among young children and domestic animals in rural Bangladesh not explained by traditional fecal-oral exposure pathways. Future studies should explore additional pathways and assess whether sanitation and animal management improvements can reduce AMR.

This study explores how riverine communities in Sirajganj adapt to recurring extreme climate events, aiming to fill the gap in localized climate resilience research. Rural riverine populations in flood, heatwave and erosion-prone areas face compounded livelihood vulnerabilities. We explored the climate vulnerabilities and resilience strategies of communities in char and mainland areas using an exploratory qualitative approach. We conducted eight focus group discussions (FGDs) with 82 participants across different age and gender groups and data were analyzed using thematic approach. Our findings reveal that extreme weather events exacerbate food insecurity, economic instability, and social vulnerabilities, particularly for women and marginalized groups. Char dwellers face heightened risks due to recurrent displacement, loss of agricultural productivity, and limited access to essential services. While communities have developed various adaptation strategies, including structural modifications to homes (e.g., raised plinth housing), behavioral adjustments, social network support, and indigenous knowledge-based techniques, these measures remain largely reactive rather than anticipatory. A shift towards anticipatory action—such as climate-informed planning, early warning systems, long-term livelihood diversification, and investment in resilient infrastructure—is critical for building sustainable resilience. These findings provide valuable insights for national planners, NGOs, and international donors aiming to strengthen community-level adaptation. Moreover, existing global and national climate vulnerability indices often fail to incorporate localized adaptation strategies and socio-economic resilience factors, limiting their applicability to high-risk communities. This study highlights the necessity of integrating regional findings into vulnerability indicators to ensure a more accurate assessment of climate risks and adaptation capacity. The study also contributes to the climate resilience literature by signifying the importance of incorporating localized adaptation practices into broader vulnerability frameworks.

Numerous trials have evaluated the effectiveness of mass drug administration (MDA) in rapidly reducing malaria transmission, but it is unknown whether the estimated effects generalize to other populations eligible for MDA. A recent cluster randomized trial in Senegal found that MDA reduced malaria incidence by 55% in areas that routinely deploy seasonal malaria chemoprevention (SMC). Here, we used transportability models with machine learning to generalize trial effects to 116 non-trial communes where SMC is the standard of care. Accounting for differences in weather, vegetation and population density between trial and non-trial areas, we estimated considerable reductions in incidence (ranging from 36% to 65%) in 74 non-trial communes, with larger decreases in areas having higher precipitation, denser vegetation and lower temperatures. We found that MDA was not effective in the postintervention year in non-trial communes, supporting the notion that MDA's effects are short-lived. Our approach offers a scalable framework for generalizing trial findings to target environmentally mediated infectious disease interventions.

BACKGROUND:Weather extremes are predicted to influence pathogen exposure but their effects on specific faecal-oral transmission pathways are not well investigated. We evaluated associations between extreme rain and temperature during different antecedent periods (0-14 days) and Escherichia coli along eight faecal-oral pathways in rural Bangladeshi households. METHODS:We used data from the WASH Benefits Bangladesh cluster-randomised controlled trial (NCT01590095). E coli was enumerated in hand rinses from children younger than 5 years and their mothers, food, stored drinking water, tubewells, captured flies, ponds, and courtyard soil using IDEXX Quanti-Tray/2000 in nine rounds over 3·5 years and spatiotemporally matched to daily weather data. We used generalised linear models with robust standard errors to estimate E coli count ratios (ECRs) associated with extreme rain and temperature, defined as greater than the 90th percentile of daily values during the study period. FINDINGS:A total of 26 659 samples were collected during the study period. Controlling for temperature, extreme rain on the sampling day was associated with increased E coli in food (ECR=3·13 [95% CI 1·63-5·99], p=0·0010), stored drinking water (ECR=1·98 [1·36-2·88], p=0·0004), and ponds (ECR=3·46 [2·34-5·11], p<0·0001), and reduced E coli in soil (ECR=0·36 [0·24-0·53], p<0·0001). Extreme rain the day before sampling was associated with reduced E coli in tubewells (ECR=0·10 [0·02-0·62], p=0·014). Associations were similar for rainfall 1-7 days before sampling and slightly attenuated for rainfall 14 days before sampling. Controlling for rainfall, extreme temperature on the sampling day was associated with increased E coli in stored drinking water (ECR=1·49 [1·05-2·12], p=0·025) and food (ECR=3·01 [1·51-6·01], p=0·0020). Associations with temperature were similar for all antecedent periods and particularly pronounced for food. Neither rainfall nor temperature were consistently associated with E coli on hands and flies. INTERPRETATION:In rural Bangladesh, measures to control enteric infections following weather extremes should focus on water treatment and safe storage to reduce contamination of drinking water and food stored at home and on reducing exposure to surface waters. FUNDING:Bill & Melinda Gates Foundation, National Institutes of Health, World Bank.

Numerous trials have evaluated the effectiveness of mass drug administration (MDA) to rapidly reduce malaria transmission, but it is unknown whether estimated effects generalize to other populations eligible for MDA. A recent cluster-randomized trial in Senegal found that MDA reduced malaria incidence by 55% in areas routinely deploying seasonal malaria chemoprevention (SMC). Here, we used transportability models with machine learning to generalize trial effects to 116 non-trial Communes where SMC is standard-of-care. Accounting for differences in weather, vegetation, and population density between trial and non-trial areas, we estimated significant reductions in incidence of 36%-65% in 74 non-trial Communes, with larger reductions in areas with higher precipitation, denser vegetation, and lower temperatures. We found that MDA was not effective in the post-intervention year in non-trial Communes, supporting the notion that MDA effects are short-lived. Our approach offers a scalable framework for generalizing trial findings to target environmentally-mediated infectious disease interventions.

Shorter telomere length (TL) is associated with an increased risk for developing chronic or age-related diseases in adults. The process of telomere shortening is accelerated in response to stress and is well characterized in adult populations from high-income countries. Prior studies suggest the relationship between stress, shorter TL, and disease risk initiates in early life. Nested within the WASH Benefits Bangladesh trial, we examined associations between parental stressors, including maternal exposure to intimate partner violence (IPV), maternal depressive symptoms, and parental perceived stress, and child TL in rural Bangladesh. We measured whole blood relative TL in 660 children at median age 14 months and 702 children at median age 28 months. We estimated mean differences between the 25th and 75th percentile or absence and presence of each exposure using generalized additive models. IPV during pregnancy was associated with more TL attrition between 14 and 28 months (− 0.32 (95% CI − 0.64, − 0.01), p-value 0.05). This association was not significant after correction for multiple comparisons. Other parental psychosocial stressors were not associated with child TL outcomes at 14 or 28 months of age in rural Bangladesh. Telomere biology during early-life development may vary across settings.

ABSTRACT Soil household floors are common in low- and middle-income countries (LMICs) and can serve as reservoirs of enteric pathogens. Cement-based floors may interrupt pathogen transmission, but little is known about pathogen survival or removal from cement-based surfaces. This study investigated the survival of Escherichia coli , an indicator of fecal contamination, on cement-based surfaces and evaluated its reduction through common household activities (mopping, sweeping, and walking). We compared E. coli fate on three mixes: (i) ordinary Portland cement (OPC) concrete (used in the United States), (ii) OPC mortar (used in Bangladesh), and (iii) OPC mortar with fly ash (a sustainable alternative to the Bangladesh mix). Additionally, we compared outcomes on cement-based surfaces with and without soil and at two temperatures representing the dry and wet seasons in Bangladesh. After 4 hours on the cement-based surfaces, E. coli decayed more than 1.1 log 10 ( C / C o ) under all conditions tested, which is significantly faster than in bulk soils. The higher temperature increased the decay rate constant ( P = 5.56 × 10 −8 ) while soil presence decreased it ( P = 2.80 × 10 −6 ). Sweeping and mopping resulted in high levels of removal for all mixes, with a mean removal of 71% and 78%, respectively, versus 22% for walking. The concrete and mortar mix designs did not impact E. coli survival or removal ( P > 0.20). Cement-based floors made with a fly ash mix performed similarly to traditional cement-based floors, supporting their potential use as a more sustainable intervention to reduce fecal contamination in rural LMIC household settings. IMPORTANCE Cement-based surfaces may serve as a health intervention to reduce the fecal-oral transmission of pathogens in household settings, but there is a critical lack of evidence about the fate of indicator organisms on these surfaces, especially in field-relevant conditions. This study provides some of the first insights into Escherichia coli survival on cement-based surfaces and the effectiveness of daily activities for removing E. coli . Additionally, this study explores the fate of E. coli on cement-based surfaces made with fly ash (which contributes fewer CO 2 emissions) versus traditional cement mixes. We found that E. coli had similar survival and removal efficiencies across all mix designs, demonstrating that fly ash mixes are feasible for use in household settings (e.g., in floors). The findings enhance understanding of fecal-oral transmission pathways and support the use of fly ash mixes in cement-based flooring in future epidemiologic studies assessing effects on enteric disease burdens.

Soil floors are common in low-income countries and can harbor contamination from unsafely managed human and animal fecal waste. Soil/dust ingestion directly from floors or indirectly via hands, drinking water and food can significantly contribute to children’s ingestion of fecal organisms. We assessed if finished (e.g., concrete) floors are associated with lower E. coli contamination in the domestic environment in rural Bangladesh. We collected samples from 1864 households over 3.5 years, including stored drinking water, child and caregiver hand rinses, courtyard soil, food, and flies (n=24,118 samples), and enumerated E. coli using IDEXX Quanti-Tray/2000. Controlling for potential confounders (socio-demographics, water/sanitation status, animal ownership), households with finished floors had slightly lower log10-transformed E. coli counts (Δlog10= -0.10 (-0.20, 0.00)) and prevalence (prevalence ratio=0.90 (0.83, 0.98)) on child hands than households with soil floors; floor material was not associated with contamination levels in other sample types. Finished floors were associated with lower E. coli contamination of child hands, food and stored drinking water following periods of higher rainfall and temperature, and lower E. coli contamination of child hands in households with more domestic animals. Measures to control enteric infections in low-income countries should test flooring improvements to reduce exposure to fecal contamination.

Background:Low-cost, household-level water, sanitation, and hygiene (WASH) and nutrition interventions can reduce pediatric antibiotic use, but the mechanism through which interventions reduce antibiotic use has not been investigated. Methods:We conducted a causal mediation analysis using data collected between September 2013 and October 2015 from a cohort nested within the WASH Benefits Bangladesh cluster-randomized trial (NCT01590095). Among a subsample of children within the WASH, nutrition, nutrition + WASH, and control arms (N = 1409 children; 267 clusters), we recorded caregiver-reported antibiotic use at ages 14 and 28 months and collected stool at age 14 months. Our primary outcome was any caregiver-reported antibiotic use by index children within the past 30 or 90 days measured at age 14 and 28 months. Mediators included caregiver-reported child diarrhea, acute respiratory infection (ARI), and fever; and enteric pathogen carriage in stool measured by qPCR. Both intervention-mediator and mediator-outcome models were controlled for mediator-outcome confounders. Findings:The receipt of any WASH or nutrition intervention reduced caregiver-reported antibiotic use through all pathways in the past month by 5.5 percentage points (95% CI 1.2, 9.9), from 49.5% (95% CI 45.9%, 53.0%) in the control group to 45.0% (95% CI 42.7%, 47.2%) in the pooled intervention group. When separating this effect into different pathways, we found that interventions reduced antibiotic use by 0.6 percentage points (95% CI 0.1, 1.3) through reduced diarrhea, 0.7 percentage points (95% CI 0.1, 1.5) through reduced ARI with fever, and 1.5 percentage points (95% CI 0.4, 3.0) through reduced prevalence of enteric viruses. Interventions reduced antibiotic use through any of these measured mediators by 2.1 percentage points (95% CI -0.3, 4.5). Interpretation:WASH and nutrition interventions reduced pediatric antibiotic use through the prevention of enteric and respiratory infections in a rural, low-income population. Given that many of these infections are caused by viruses or parasites, WASH and nutrition interventions may help reduce inappropriate antibiotic use in similar settings. Funding:Bill & Melinda Gates Foundation, National Institute of Allergy and Infectious Diseases.

Global health programs have traditionally focused on single diseases. There is potential for synergy through integrated intervention delivery, particularly in areas with overlapping geographic disease burden, but there is limited methodology developed for assessing potential efficiency gains through integration. Here, we applied a measure of diversity, Rao's quadratic index, to quantify multipathogen burden across two large-scale surveys: Bangladesh (90 clusters, 2,396 children) and Cambodia (100 clusters, 2,150 women). In both settings, we observed geographic clustering of multiple pathogens, indicating potential for more efficient, integrated disease control strategies. We assessed the efficiency of a multipathogen-targeted strategy compared to traditional single-pathogen approaches by calculating the percent reduction in the number of spatial clusters needed to reach 75% of the disease burden (infections or unvaccinated individuals) in a hypothetical intervention. In Bangladesh, integrating deworming with measles vaccination guided by Rao's quadratic index improved efficiency by 15% for Ascaris lumbricoides, 31% for hookworm, and 38% for Trichuris trichiura, compared to a measles-focused approach. In Cambodia, a Rao-guided strategy performed similarly to the best single-pathogen strategy for Strongyloides stercoralis, and reduced the number of spatial clusters that would need to be targeted by 57% (lymphatic filariasis), 83% (Plasmodium falciparum), and 59% (Plasmodium vivax). We also found that higher multipathogen burden was significantly associated with lower household wealth, suggesting that Rao-guided strategies may be more effective in reaching under-resourced populations. These findings support the use of multipathogen burden metrics to guide integrated program delivery, offering potential for greater efficiency in disease control.

Weather can influence the environmental spread and survival of fecal pathogens, potentially affecting the effectiveness of water, sanitation, and hygiene (WASH) interventions. We assessed whether rainfall and temperature modified effects of an on-site sanitation intervention on fecal contamination among households in the WASH Benefits trial in rural Bangladesh. The intervention included double-pit latrines, potties, feces removal tools and behavior change promotion. We longitudinally visited households from intervention and control groups to enumerate E. coli. Samples (n = 23,238) included drinking water from tubewells and storage containers, prepared food, caregiver and child hand rinses, pond water, courtyard soil, and flies. We geospatially matched E. coli measurements to daily weather data and estimated intervention effects with and without stratification by weather. The intervention resulted in greater reduction in contamination following higher rainfall for four pathways (mother/child hands, ponds, flies), and following higher temperatures for five pathways (food, mother/child hands, soil, ponds). Compared to controls, E. coli levels were reduced by approximately 1-log for flies and 0.25-log in ponds after higher rainfall, 0.2-log on child hands, 0.3-0.4 log in soil and ponds after higher temperatures (interaction p-values<0.20), and 0.1-log in stored drinking water under most conditions. Intervention effects were minimal when not stratified by weather, with <0.1-log reductions for stored drinking water and child hands, and no effects on other pathways. Sanitation interventions may deliver greater protection against environmental contamination during wetter, warmer conditions, and assessments that average over time may conceal differential intervention effects. WASH trials should incorporate spatiotemporal weather data into impact evaluations.

Understanding whether influenza vaccine promotion strategies produce community-wide indirect effects is important for establishing vaccine coverage targets and optimizing vaccine delivery. Empirical epidemiologic studies and mathematical models have been used to estimate indirect effects of vaccines but rarely for the same estimand in the same data set. Using these approaches together could be a powerful tool for triangulation in infectious disease epidemiology because each approach is subject to distinct sources of bias. We triangulated evidence about indirect effects from a school-located influenza vaccination program using 2 approaches: a difference-in-difference (DID) analysis and an age-structured, deterministic, compartmental model. The estimated indirect effect was substantially lower in the mathematical model than in the DID analysis (2.1% [95% Bayesian credible intervals, 0.4%-4.4%] vs 22.3% [7.6%-37.1%]). To explore reasons for differing estimates, we used sensitivity analyses and probabilistic bias analyses. When we constrained model parameters such that projections matched the DID analysis, results only aligned with the DID analysis with substantially lower preexisting immunity among school-age children and older adults. Conversely, DID estimates corrected for potential bias only aligned with mathematical model estimates under differential outcome misclassification. We discuss how triangulation using empirical and mathematical modeling approaches could strengthen future studies.

Cluster randomised trials (CRTs) are important tools for evaluating the community-wide effect of malaria interventions. During the design stage, CRT sample sizes need to be inflated to account for the cluster heterogeneity in measured outcomes. The coefficient of variation (k), a measure of such heterogeneity, is typically used in malaria CRTs yet is often predicted without prior data. Underestimation of k decreases study power, thus increases the probability of generating null results. In this meta-analysis of cluster-summary data from 24 malaria CRTs, we calculate true prevalence and incidence k values using methods-of-moments and regression modelling approaches. Using random effects regression modelling, we investigate the impact of empirical k values on original trial power and explore factors associated with elevated k. Results show empirical estimates of k often exceed those used in sample size calculations, which reduces study power and effect size precision. Elevated k values are associated with incidence outcomes (compared to prevalence), lower endemicity settings, and uneven intervention coverage across clusters. Study findings can enhance the robustness of future malaria CRT sample size calculations by providing informed k estimates based on expected prevalence or incidence, in the absence of cluster-level data.