Public health impact of catch-up vaccination or additional booster doses with pre-erythrocytic malaria vaccine R21/Matrix-M: a modelling study
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Author(s)
Type
Journal Article
Abstract
Background
The malaria vaccine R21/Matrix-M is recommended for young children in malaria-endemic regions. However, the small vaccine-eligible population and waning vaccine efficacy mean that routine vaccination is unlikely to prevent severe cases in older children who experience significant malaria burden. As R21/Matrix-M vaccination expands, targeting older age groups may be warranted, depending on funding.
Methods
Using a stochastic, individual-based P. falciparum malaria transmission model, we estimate the impact of 1) one-off catch-up campaigns with R21/Matrix-M to previously unvaccinated age groups between age 6 months and 14 years, and/or 2) extra boosters at 2, 5 and/or 10 years after the primary series in low, moderate, and high transmission settings. We assume that vaccine immunogenicity in older children is equivalent to that of the standard target age group, though clinical trials have shown lower immunogenicity in older children.
Results
Catch-up campaigns in moderate-to-high transmission settings targeting younger children averted the most uncomplicated cases per 1000 additional doses (358 (95% Credible Interval (CI) 113-570) in children aged 6 months-2 years at 45% PfPR2-10), compared with targeting older children. In low transmission settings, the impact was similar across age groups, with a slightly higher impact when targeting school-aged children (373 (95% CrI 240-518) in children aged 5-9 years at 5% PfPR2-10). Across extra booster strategies, an extra booster 10 years post-primary series averted the most severe cases per 1000 additional doses at low transmission (12 (95% CrI 6-18) at 5% PfPR2-10), but the least at high transmission (-4 (95% CrI -11-3) at 45% PfPR2-10).
Expanding the vaccine-eligible population in areas of moderate-to-high transmission often had higher incremental efficiency than routine age-based vaccination at low transmission. Sensitivity analyses assuming lower immunogenicity in older children modestly reduced the per-dose impact (median reduction of 16.1% for clinical cases, 15.0% for severe cases), but overall conclusions remained unchanged.
Conclusions
Catch-up campaigns or extra booster doses of R21/Matrix-M can provide benefits beyond routine administration, with the per-additional-dose value approaching that of routine vaccination, but this varies by transmission and seasonality setting. Further empirical studies, particularly on vaccine efficacy in older children, are warranted to inform policy guidance for malaria vaccination implementation.
The malaria vaccine R21/Matrix-M is recommended for young children in malaria-endemic regions. However, the small vaccine-eligible population and waning vaccine efficacy mean that routine vaccination is unlikely to prevent severe cases in older children who experience significant malaria burden. As R21/Matrix-M vaccination expands, targeting older age groups may be warranted, depending on funding.
Methods
Using a stochastic, individual-based P. falciparum malaria transmission model, we estimate the impact of 1) one-off catch-up campaigns with R21/Matrix-M to previously unvaccinated age groups between age 6 months and 14 years, and/or 2) extra boosters at 2, 5 and/or 10 years after the primary series in low, moderate, and high transmission settings. We assume that vaccine immunogenicity in older children is equivalent to that of the standard target age group, though clinical trials have shown lower immunogenicity in older children.
Results
Catch-up campaigns in moderate-to-high transmission settings targeting younger children averted the most uncomplicated cases per 1000 additional doses (358 (95% Credible Interval (CI) 113-570) in children aged 6 months-2 years at 45% PfPR2-10), compared with targeting older children. In low transmission settings, the impact was similar across age groups, with a slightly higher impact when targeting school-aged children (373 (95% CrI 240-518) in children aged 5-9 years at 5% PfPR2-10). Across extra booster strategies, an extra booster 10 years post-primary series averted the most severe cases per 1000 additional doses at low transmission (12 (95% CrI 6-18) at 5% PfPR2-10), but the least at high transmission (-4 (95% CrI -11-3) at 45% PfPR2-10).
Expanding the vaccine-eligible population in areas of moderate-to-high transmission often had higher incremental efficiency than routine age-based vaccination at low transmission. Sensitivity analyses assuming lower immunogenicity in older children modestly reduced the per-dose impact (median reduction of 16.1% for clinical cases, 15.0% for severe cases), but overall conclusions remained unchanged.
Conclusions
Catch-up campaigns or extra booster doses of R21/Matrix-M can provide benefits beyond routine administration, with the per-additional-dose value approaching that of routine vaccination, but this varies by transmission and seasonality setting. Further empirical studies, particularly on vaccine efficacy in older children, are warranted to inform policy guidance for malaria vaccination implementation.
Date Issued
2026-12-01
Date Acceptance
2026-03-20
Citation
BMC Medicine, 2026, 24
ISSN
1741-7015
Publisher
BMC
Journal / Book Title
BMC Medicine
Volume
24
Copyright Statement
© The Author(s) 2026. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Identifier
10.1186/s12916-026-04822-y
Publication Status
Published
Article Number
ARTN 286
Date Publish Online
2026-03-25