Implementation and fidelity of reactive surveillance and response strategies for malaria elimination: a systematic review and meta-analysis.

Introduction: To achieve malaria elimination, case-based surveillance and response systems have been developed in endemic countries. This study systematically reviews the different types of reactive surveillance and response strategies for malaria, how they are being implemented, and their implementation fidelity, across different malaria elimination settings to inform reactive surveillance and response guidelines. Methods: A systematic review of published and grey quantitative and qualitative studies investigating different reactive surveillance and response strategies was conducted. Five databases (PubMed, Web of Science, Scopus, African Index Medicus and Latin American and Caribbean Health Sciences Literature) were searched in all years up to 16 June 2025 with no restrictions on language or publication date. Meta-analyses were performed to obtain pooled estimates of each implementation fidelity outcome of reactive surveillance and responses. Sub-group analyses of geographical regions were performed. Results: 69 studies (33 in the Asia-Pacific, including 16 in Greater Mekong Subregion, 34 in Africa and two in South America regions) were included in the review; of which 43 were included in the meta-analysis. The '1-3-7' strategy is a common reactive surveillance and response strategy developed in China and adopted by Greater Mekong Subregion countries. In Africa, many countries undertook reactive case detection alone as their reactive surveillance and response strategy (19/34 studies). In general, the implementation fidelity measured by completeness and timeliness of each step of reactive surveillance and responses was 100% in China (completeness and timeliness of case investigation: 100% (95% CI 100% to 100%) and 97% (95% CI 93% to 100%), respectively). Lowest fidelities of reactive surveillance and responses were observed in studies conducted in Africa and Greater Mekong Subregion (timeliness of case investigation: 56% (95% CI 26% to 83%) in Africa and 57% (95%CI 37% to 77%) in Greater Mekong Subregion). Conclusion: The implementation fidelity of reactive surveillance and responses varies within and across countries and regions. This may be due to differences in regional, national and sub-national health system capacity and infrastructure. Each endemic country implementing the malaria elimination programme should reevaluate, refine, improve and strengthen the ongoing strategy which is fit-for-purpose of the national health system capacity considering the global and regional evidence. Trial registration number: International prospective register of systematic reviews (PROSPERO), CRD42021249857.