Who are the hard-to-reach population? Spatial analysis from a cross-sectional study on the access to bed net and malaria vaccine in the Lake Victoria Region, Kenya

Background Long-lasting insecticidal nets (LLIN) and vaccines are effective malaria control tools. However, inadequate uptake has been reported in countries where both interventions are available. To maximize the impact these tools provide, it is crucial to identify populations that are not being reached and the barriers to uptake. Methods In a cross-sectional study conducted in April 2024 in Kanyamwa Kologi Ward in Homa Bay County, Kenya, 4,662 households in 58 randomely selected villages were visited and interviewed. We examined the proportions of households that: 1) received at least one new LLIN within the previous five months (net distribution), 2) reported all children used LLIN (net usage), 3) reported at least one child had received one dose of the RTS,S vaccine (vaccine uptake), and 4) reported all children had received four doses of the vaccine (vaccine completion). Bayesian spatial autoregression analyses were used to identify the association and its credible intervals (CrI) between the household-level characteristics and the four outcomes. Results The overall uptake proportions were 89.9% for net distribution, 84.4% for net usage, 88.2% for vaccine uptake, and 53.7% for vaccine completion. All four outcomes showed geographical heterogeneity with significant (p < 0.05) Moran's I. Households headed by adults of >40 years had higher odds of having received a new LLIN (OR=1.85, 95% CrI 0.93–4.61), having one child who had received one vaccine dose (OR=1.83, 0.69–4.66), and having all children fully vaccinated (OR=2.36, 1.09–5.46), but lower odds of net usage by all children (OR=0.62, 0.40–0.96). Households with five or more children had higher odds of having received a new LLIN (OR=5.51, 1.69–53.8) but lower odds of net usage by all children (OR=0.24, 0.14–0.38) and having all children fully vaccinated (OR=0.20, 0.04–0.61). Distance to the nearest health center was negatively associated with all outcomes. Household wealth was positively associated with all outcomes. Conclusion Uptake of LLIN and malaria vaccine in Homa Bay County, Kenya varied by geography and household characteristics. These findings suggest the need for targeted, outcome-specific interventions to enhance overall public health policy uptake in malaria prevention.