From near-elimination to resurgence: a comparative analysis of two mass drug administration campaigns on Grande Comore Island (2013–2024)
5 affiliations
- 1Artemisinin Research Center, Guangzhou University of Chinese Medicine, Jichang Road No.12, Baiyun District, Guangzhou, 510405 China
- 2Institution of Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510405 People’s Republic of China
- 3Zhang Zhongjing School of Chinese Medicine, Nanyang Institute of Technology, Nanyang, 571756 People’s Republic of China
- 4National Malaria Control Programme of the Union of Comoros, Moroni, Union of the Comoros
- 5State Key Laboratory for Quality Ensurance and Sustainable Useof Dao-diHerbs, Beijing, 100700 People’s Republic of China
Abstract
Background: Mass drug administration (MDA) achieved sustained malaria elimination on Mohéli and Anjouan but only transient control on Grande Comore. Following resurgence from 1061 cases in 2015 to 19,453 in 2018, a renewed MDA campaign was implemented on Grande Comore in 2019. This study evaluates its effectiveness compared to the 2013 campaign to identify determinants of sustained suppression.
Methods: Two rounds of artemisinin‑piperaquine plus single low‑dose primaquine were administered in September–October 2019, targeting 348,961 residents. MDA coverage, adverse events, and parasitological outcomes from surveys at four time points were assessed. Monthly confirmed cases from 2012–2024 were analyzed descriptively to compare the epidemiological trajectories following the 2013 and 2019 campaigns, acknowledging that this historical comparison with multiple co‑varying confounders does not permit causal attribution.
Results: Round 1 coverage was 83.5%, declining to 58.0% in Round 2 (p = 0.0008). Adverse events occurred in 0.3% of doses, with no severe events reported. Parasitemia declined by 92.7% after Round 1 and remained 96.5% below baseline at 15 months. Reported monthly cases declined by 79.7% from the pre‑MDA mean (1,731 cases/month) to the early post‑MDA mean (352 cases/month), reaching a nadir of 192 cases in April 2020—an 88.2% reduction from baseline (1,621 cases/month). However, this nadir coincided with the first COVID‑19 lockdown, which likely reduced healthcare access and reporting completeness. Cases remained below the 50% threshold (810 cases/month) for 19 consecutive months but rebounded to 53.7% above baseline by 2022–2024. In descriptive comparison with the 2013 campaign (99.1% reduction, > 48 months suppression), the 2019 campaign showed a lower reduction (88.2%) and shorter suppression duration (19 months). Spatially, resurgence after the 2013 campaign was relatively focal, while after the 2019 campaign it became more widespread—a pattern consistent with a larger or more dispersed residual parasite reservoir.
Conclusions: The 2019 MDA was followed by less durable suppression than observed after the 2013 campaign. Declining second‑round coverage, weaker post‑MDA surveillance, and COVID‑19‑related disruptions may have contributed, but the historical comparison involves multiple confounders and precludes causal attribution. These findings should be interpreted as hypothesis‑generating for future malaria elimination strategies.
Trial registration The study protocol was approved by the National Health Ethics Committee of the Union of Comoros (No. 12521/MSSPG/CAB) on 13 September 2012, the Guangzhou University of Chinese Medicine Ethics Committee for Health Research (No. 2012L0816) on 25 September 2012, and the Ethical Board of Guangdong Provincial Hospital of Chinese Medicine (No. BF2019-169-01) on 18 October 2019.
Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1186/s12936-026-06080-y.
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BibTeX
@article{li2026from,
title = {{From near-elimination to resurgence: a comparative analysis of two mass drug administration campaigns on Grande Comore Island (2013–2024)}},
author = {Mingqiang Li and Yueming Yuan and Hongying Zhang and Chenguang Lu and Ruimei Liu and Lei Shu and Wei Xie and Ruixiang Tan and Kamal Said Abdallah and Wanting Wu and Salim Abdoulkarim Mmadi and Zhengjie Yu and Affane Bacar and Weihe Chen and Nadia Julie and Jianping Song and Changsheng Deng and Guoming Li},
journal = {Malaria Journal},
year = {2026},
month = aug,
doi = {10.1186/s12936-026-06080-y},
url = {https://doi.org/10.1186/s12936-026-06080-y},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - From near-elimination to resurgence: a comparative analysis of two mass drug administration campaigns on Grande Comore Island (2013–2024)
AU - Mingqiang Li
AU - Yueming Yuan
AU - Hongying Zhang
AU - Chenguang Lu
AU - Ruimei Liu
AU - Lei Shu
AU - Wei Xie
AU - Ruixiang Tan
AU - Kamal Said Abdallah
AU - Wanting Wu
AU - Salim Abdoulkarim Mmadi
AU - Zhengjie Yu
AU - Affane Bacar
AU - Weihe Chen
AU - Nadia Julie
AU - Jianping Song
AU - Changsheng Deng
AU - Guoming Li
PY - 2026
DA - 2026/08/01
JO - Malaria Journal
DO - 10.1186/s12936-026-06080-y
UR - https://doi.org/10.1186/s12936-026-06080-y
AB - Background: Mass drug administration (MDA) achieved sustained malaria elimination on Mohéli and Anjouan but only transient control on Grande Comore. Following resurgence from 1061 cases in 2015 to 19,453 in 2018, a renewed MDA campaign was implemented on Grande Comore in 2019. This study evaluates its effectiveness compared to the 2013 campaign to identify determinants of sustained suppression. Methods: Two rounds of artemisinin‑piperaquine plus single low‑dose primaquine were administered in September–October 2019, targeting 348,961 residents. MDA coverage, adverse events, and parasitological outcomes from surveys at four time points were assessed. Monthly confirmed cases from 2012–2024 were analyzed descriptively to compare the epidemiological trajectories following the 2013 and 2019 campaigns, acknowledging that this historical comparison with multiple co‑varying confounders does not permit causal attribution. Results: Round 1 coverage was 83.5%, declining to 58.0% in Round 2 (p = 0.0008). Adverse events occurred in 0.3% of doses, with no severe events reported. Parasitemia declined by 92.7% after Round 1 and remained 96.5% below baseline at 15 months. Reported monthly cases declined by 79.7% from the pre‑MDA mean (1,731 cases/month) to the early post‑MDA mean (352 cases/month), reaching a nadir of 192 cases in April 2020—an 88.2% reduction from baseline (1,621 cases/month). However, this nadir coincided with the first COVID‑19 lockdown, which likely reduced healthcare access and reporting completeness. Cases remained below the 50% threshold (810 cases/month) for 19 consecutive months but rebounded to 53.7% above baseline by 2022–2024. In descriptive comparison with the 2013 campaign (99.1% reduction, > 48 months suppression), the 2019 campaign showed a lower reduction (88.2%) and shorter suppression duration (19 months). Spatially, resurgence after the 2013 campaign was relatively focal, while after the 2019 campaign it became more widespread—a pattern consistent with a larger or more dispersed residual parasite reservoir. Conclusions: The 2019 MDA was followed by less durable suppression than observed after the 2013 campaign. Declining second‑round coverage, weaker post‑MDA surveillance, and COVID‑19‑related disruptions may have contributed, but the historical comparison involves multiple confounders and precludes causal attribution. These findings should be interpreted as hypothesis‑generating for future malaria elimination strategies. Trial registration The study protocol was approved by the National Health Ethics Committee of the Union of Comoros (No. 12521/MSSPG/CAB) on 13 September 2012, the Guangzhou University of Chinese Medicine Ethics Committee for Health Research (No. 2012L0816) on 25 September 2012, and the Ethical Board of Guangdong Provincial Hospital of Chinese Medicine (No. BF2019-169-01) on 18 October 2019. Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1186/s12936-026-06080-y.
SN - 1475-2875
ER -