Peer-reviewed article
Assessing the impact of routine malaria vaccination on total disease burden in Cameroon: a nationwide difference‑in‑differences analysis using health district surveillance data (2023–2025)
Cavin Epie Bekolo, Nina Ngouenko, Esther Laura Nyame Dipepa Nwall, Leonard Ewane ·
Summary
Written by AI, not yet AICS's view · claude-sonnet-5-5This study looked at whether Cameroon's routine RTS,S malaria vaccine, introduced in 2024 in 42 priority health districts, reduced malaria burden. It compared 42 districts with the vaccine and 164 without, using routine surveillance data from 2023 to 2025. Simple comparisons showed larger declines in malaria cases, hospitalisations and deaths in vaccine districts. However, once the analysis was adjusted for district and year differences, the effects were not statistically significant. The authors say selection bias and low power likely explain this, and they support continued vaccine scale-up.
Key points
- Intervention districts had higher baseline ITN coverage (60.2% vs 45.5%) and IPT coverage (35.1% vs 24.4%) than non-intervention districts.
- Crude difference-in-differences showed a 2.6 per 1,000 (15%) reduction in severe malaria and a 4.1 per 100,000 (26%) reduction in malaria deaths.
- Adjusted linear DiD estimates were not statistically significant (severe malaria coefficient -0.54, 95% CI -11.07 to 9.99, p = 0.920).
- Subgroup analyses suggested the largest effect in the Sahel (crude rate ratio 0.78) and added benefit when combined with SMC (additional 5.6 per 1,000 reduction).
- The authors estimated that in 2025 vaccination averted 7,200 severe cases, 5,300 hospitalisations and 77 deaths.
Limitations
The study is non-randomised and ecological, using district-level routine data, and baseline differences between districts suggest selection bias. The adjusted results were null and the study likely had low power, so it cannot show a clear causal effect of the vaccine.
Abstract
BACKGROUND: Cameroon introduced the RTS, S/AS01 malaria vaccine into routine expanded immunisation (EPI) in 2024, targeting 42 priority health districts. We assessed changes in total malaria burden between intervention and non-intervention districts over 2023-2025. METHODS: We conducted a retrospective, quasi-experimental, ecological longitudinal study using a difference-in-differences (DiD) approach on routine district-level surveillance data from 206 districts (42 intervention, 164 non-intervention) for 2023-2025. Outcomes included severe malaria rate (per 1,000 children < 5), uncomplicated malaria rate, all malaria-related hospitalisations, and malaria mortality rate (per 100,000). Crude pre-post changes and DiD were calculated. Adjusted linear DiD models with district and year fixed effects and cluster-robust standard errors were also fitted. Subgroup analyses examined interactions with seasonal malaria chemoprevention (SMC), intermittent preventive treatment in infants (IPTi), insecticide-treated nets (ITNs), and ecological region. RESULTS: Baseline characteristics differed significantly: intervention districts had higher ITN coverage (60.2% vs. 45.5%, p = 0.006), higher IPT coverage (35.1% vs. 24.4%, p = 0.001), and larger populations (median 121,284 vs. 89,592, p = 0.029). From 2023 to 2025, intervention districts experienced larger declines in all outcomes. Crude DiD showed a 2.6 per 1000 (15%) reduction in severe malaria, 8.1 per 1000 (22%) reduction in uncomplicated malaria, 5.3 per 1000 (28%) reduction in hospitalisations, and 4.1 per 100,000 (26%) reduction in malaria deaths. Adjusted linear DiD estimates were not statistically significant (e.g., severe malaria coefficient - 0.54, 95% CI - 11.07 to 9.99, p = 0.920). Subgroup analyses indicated the largest effects in the Sahel (crude rate ratio 0.78) and added benefit when the vaccine was combined with SMC (additional - 5.6 per 1000 reduction). In 2025 alone, vaccination averted an estimated 7,200 severe cases, 12,800 uncomplicated cases, 5,300 hospitalisations, and 77 deaths. CONCLUSION: Crude trends show favourable declines in malaria burden in intervention districts, but adjusted estimates were null, likely due to selection bias and low power. These findings support continued vaccine scale-up and use of routine data for monitoring, while acknowledging the limitations of non-randomised evaluations.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- Routine RTS,S/AS01 malaria vaccination introduced through the EPI in 42 priority health districts in 2024
- Population
- Children under 5 in 206 Cameroonian health districts (42 with the vaccine, 164 without), 2023-2025
Key finding
Crude DiD: 2.6 per 1,000 (15%) reduction in severe malaria and 8.1 per 1,000 (22%) reduction in uncomplicated malaria
Bekolo et al. · OpenAlex · 30 Sept 2026