Uncovering the spatiotemporal patterns of the largest vaccine-derived poliovirus serotype 2 outbreak in the Democratic Republic of the Congo

Uncovering the spatiotemporal patterns of the largest vaccine-derived poliovirus serotype 2 outbreak in the Democratic Republic of the Congo | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Uncovering the spatiotemporal patterns of the largest vaccine-derived poliovirus serotype 2 outbreak in the Democratic Republic of the Congo Darlan da Silva Candido, Kieran Chopra, Tresor Kabeya Mampuela, and 10 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9097051/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Vaccine-derived poliovirus serotype 2 (VDPV2) outbreaks are a major challenge to polio eradication, seeded by rare reversions of oral polio vaccine to a neurovirulent strain. The Democratic Republic of the Congo has experienced more VDPV2 outbreaks than any other country; however, little is known about the subnational dynamics of VDPV2 spread, and understanding of the quality of VDPV2 surveillance and outbreak response in the country is incomplete. We used phylodynamic and phylogeographic methods to analyse 116 VP1 sequences from cases of poliomyelitis associated with RDC-MAN-3, the largest VDPV2 outbreak to date in the DRC with cases reported between October 2021 and August 2023, alongside programmatic data from the RDC-MAN-3 outbreak. We identified a pair of vaccination campaigns in Tshopo in October 2020 as the most plausible seeding event, making the delay between seeding and first discovery by environmental sampling approximately 12 months. Phylogeographic reconstruction showed predominantly local spread, with a median of 74% (20/27) of inferred cross-province movements occurring between neighbouring provinces. and identified pairs of provinces with the most important contributions to spatial dispersal of the outbreak; in particular, transmission from Tanganyika to Haut Lomami was highly frequent (9/27 cross-province movements). We inferred from the effective population size trajectory that surveillance was likely less intensive in the first wave of the outbreak, and that in some provinces RDC-MAN-3 was introduced at least two months before detection, while in Équateur province RDC-MAN-3 was never detected by culture testing. Finally, our analysis found that outbreak response vaccination campaigns were conducted 2-13 months (modal average across provinces of 5 months) after the estimated importation of poliovirus into each province. These results show how campaign scope and timing were insufficient to stop the outbreak early and highlight how routine genomic data can retrospectively assess the adequacy of surveillance and response implementation. Biological sciences/Computational biology and bioinformatics/Phylogeny Biological sciences/Evolution/Phylogenetics Biological sciences/Genetics/Microbial genetics/Viral genetics Health sciences/Diseases/Infectious diseases/Viral infection Full Text Additional Declarations There is NO Competing Interest. Supplementary Files ChopraNatMicroSM.docx Supplementary Figures Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9097051","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":605117232,"identity":"f7fa670a-696d-4e58-9195-332f11580a7f","order_by":0,"name":"Darlan da Silva 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