{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,11,6]],"date-time":"2026-11-06T23:27:28Z","timestamp":1794007648064,"version":"4.8.0"},"posted":{"date-parts":[[2026,7,23]]},"group-title":"Epidemiology","reference-count":57,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T00:00:00Z","timestamp":1784764800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"award":["75N93021C00018"],"award-info":[{"award-number":["75N93021C00018"]}],"id":[{"id":"https:\/\/ror.org\/043z4tv69","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,11,6]]},"abstract":"<jats:p>Until 2020, two lineages of the influenza B virus had co-circulated globally. Measures to control the COVID-19 pandemic led to a near-absence of influenza infections. While B\/Victoria reemerged in late 2021, there have been no reports of B\/Yamagata since the pandemic. To investigate which epidemiological and immunological factors were primarily responsible for the extinction of B\/Yamagata, we developed a global model for the two influenza B lineages. To mimic the transmission impacts of the pandemic, we implemented a transient reduction in contacts and identified parameter values that recapitulated viral coexistence dynamic before the pandemic and the qualitative post-pandemic outcomes of B\/Victoria (reemergence in late 2021) and B\/Yamagata (extinction). Our results suggest that, rather than immunological or evolutionary mechanisms, the extinction of B\/Yamagata was mainly driven by its lower basic reproduction number making the virus particularly vulnerable during the early phase of the pandemic. Stochastic simulations of our best-fitting model suggest that B\/Victoria was also close to extinction during this period. We investigate the model to assess the feasibility of B\/Victoria eradication through vaccination and the potential for a sustained re-emergence of B\/Yamagata in the 2026-27 flu season, thus highlighting important considerations for biosafety.<\/jats:p>","DOI":"10.64898\/2026.07.22.26358639","type":"posted-content","created":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T23:10:20Z","timestamp":1784848220000},"source":"Crossref","is-referenced-by-count":0,"title":["Identifying the viral and epidemiological factors behind the apparent global extinction of influenza B\/Yamagata"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0318-1906","authenticated-orcid":false,"given":"Maria A.","family":"Gutierrez","sequence":"first","affiliation":[{"name":"University of Georgia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7221-3801","authenticated-orcid":false,"given":"Pejman A.","family":"Rohani","sequence":"additional","affiliation":[{"name":"University of Georgia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026081011301899000_2026.07.22.26358639v2.1","doi-asserted-by":"crossref","unstructured":"T Francis Jr ., A new type of virus from epidemic influenza. Science pp. 405\u2013408 (1940).","DOI":"10.1126\/science.92.2392.405"},{"key":"2026081011301899000_2026.07.22.26358639v2.2","doi-asserted-by":"crossref","first-page":"119","DOI":"10.2217\/fmb.15.120","article-title":"Knowns and unknowns of influenza B viruses","volume":"11","year":"2016","journal-title":"Futur. Microbiol"},{"key":"2026081011301899000_2026.07.22.26358639v2.3","doi-asserted-by":"publisher","DOI":"10.1016\/0042-6822(90)90186-U"},{"key":"2026081011301899000_2026.07.22.26358639v2.4","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1916585116"},{"key":"2026081011301899000_2026.07.22.26358639v2.5","doi-asserted-by":"publisher","DOI":"10.1006\/viro.2002.1719"},{"key":"2026081011301899000_2026.07.22.26358639v2.6","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1111\/irv.12319","article-title":"Epidemiological and virological characteristics of influenza B: results of the Global Influenza B Study","volume":"9","year":"2015","journal-title":"Influ. Other Respir. Viruses"},{"key":"2026081011301899000_2026.07.22.26358639v2.7","doi-asserted-by":"publisher","DOI":"10.1038\/nature14460"},{"key":"2026081011301899000_2026.07.22.26358639v2.8","doi-asserted-by":"crossref","unstructured":"Z Chen , et al., COVID-19 pandemic interventions reshaped the global dispersal of seasonal influenza viruses. Science 386 (2024).","DOI":"10.1126\/science.adq3003"},{"key":"2026081011301899000_2026.07.22.26358639v2.9","doi-asserted-by":"publisher","DOI":"10.1371\/journal.ppat.1006749"},{"key":"2026081011301899000_2026.07.22.26358639v2.10","doi-asserted-by":"crossref","first-page":"510","DOI":"10.1126\/science.adw4964","article-title":"Collateral effects of COVID-19 pandemic control on the US infectious disease landscape","volume":"390","year":"2025","journal-title":"Science"},{"key":"2026081011301899000_2026.07.22.26358639v2.11","doi-asserted-by":"crossref","unstructured":"V Simon , et al., The pandemic gap of respiratory viruses during the COVID-19 pandemic. mBio pp. e03376\u201325 (2025).","DOI":"10.1128\/mbio.03376-25"},{"key":"2026081011301899000_2026.07.22.26358639v2.12","doi-asserted-by":"publisher","DOI":"10.1093\/infdis\/jiab485"},{"key":"2026081011301899000_2026.07.22.26358639v2.13","doi-asserted-by":"crossref","first-page":"4164","DOI":"10.1038\/s41467-024-48528-2","article-title":"Impacts of human mobility on the citywide transmission dynamics of 18 respiratory viruses in pre-and post-COVID-19 pandemic years","volume":"15","year":"2024","journal-title":"Nat. communications"},{"key":"2026081011301899000_2026.07.22.26358639v2.14","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2001017"},{"key":"2026081011301899000_2026.07.22.26358639v2.15","doi-asserted-by":"crossref","first-page":"529","DOI":"10.1038\/s41562-021-01079-8","article-title":"A global panel database of pandemic policies (Oxford COVID-19 Government Response Tracker)","volume":"5","year":"2021","journal-title":"Nat. Hum. Behav"},{"key":"2026081011301899000_2026.07.22.26358639v2.16","doi-asserted-by":"crossref","first-page":"3481","DOI":"10.1111\/ajt.16049","article-title":"Changes in influenza and other respiratory virus activity during the COVID-19 pandemic\u2014United States, 2020\u20132021","volume":"21","year":"2021","journal-title":"Am. J. Transplantation"},{"key":"2026081011301899000_2026.07.22.26358639v2.17","doi-asserted-by":"crossref","unstructured":"S Caini , et al., Probable extinction of influenza B\/Yamagata and its public health implications: a systematic literature review and assessment of global surveillance databases. The Lancet Microbe 5 (2024).","DOI":"10.1016\/S2666-5247(24)00066-1"},{"key":"2026081011301899000_2026.07.22.26358639v2.18","doi-asserted-by":"crossref","first-page":"10440","DOI":"10.1038\/s41467-025-65396-6","article-title":"Unraveling the mechanism behind the probable extinction of the B\/Yamagata lineage of influenza B viruses","volume":"16","year":"2025","journal-title":"Nat. Commun"},{"key":"2026081011301899000_2026.07.22.26358639v2.19","doi-asserted-by":"crossref","first-page":"eadu3344","DOI":"10.1126\/sciadv.adu3344","article-title":"Neuraminidase-specific antibodies drive differential cross-protection between contemporary FLUBV lineages","volume":"11","year":"2025","journal-title":"Sci. Adv"},{"key":"2026081011301899000_2026.07.22.26358639v2.20","doi-asserted-by":"publisher","DOI":"10.7554\/elife.05055"},{"key":"2026081011301899000_2026.07.22.26358639v2.21","unstructured":"WHO (World Health Organization), https:\/\/www.who.int\/tools\/flunet (1997)."},{"key":"2026081011301899000_2026.07.22.26358639v2.22","doi-asserted-by":"publisher","DOI":"10.1038\/nature09319"},{"key":"2026081011301899000_2026.07.22.26358639v2.23","doi-asserted-by":"publisher","DOI":"10.1016\/j.vaccine.2015.09.025"},{"key":"2026081011301899000_2026.07.22.26358639v2.24","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pbio.1002056"},{"key":"2026081011301899000_2026.07.22.26358639v2.25","doi-asserted-by":"crossref","first-page":"20150347","DOI":"10.1098\/rspb.2015.0347","article-title":"Avoidable errors in the modelling of outbreaks of emerging pathogens, with special reference to Ebola","volume":"282","year":"2015","journal-title":"Proc. Royal Soc. B: Biol. Sci"},{"key":"2026081011301899000_2026.07.22.26358639v2.26","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.2012327118"},{"key":"2026081011301899000_2026.07.22.26358639v2.27","doi-asserted-by":"publisher","DOI":"10.1016\/j.jtbi.2008.04.011"},{"key":"2026081011301899000_2026.07.22.26358639v2.28","first-page":"785","article-title":"XGBoost: A Scalable Tree Boosting System","year":"2016","journal-title":"Proceedings of the 22nd ACM SIGKDD International Conference on Knowledge Discovery and Data Mining"},{"key":"2026081011301899000_2026.07.22.26358639v2.29","year":"2017","journal-title":"A Unified Approach to Interpreting Model Predictions"},{"key":"2026081011301899000_2026.07.22.26358639v2.30","doi-asserted-by":"crossref","first-page":"4313","DOI":"10.1038\/s41467-021-24566-y","article-title":"Lineage-specific protection and immune imprinting shape the age distributions of influenza B cases","volume":"12","year":"2021","journal-title":"Nat. Commun"},{"key":"2026081011301899000_2026.07.22.26358639v2.31","first-page":"379","article-title":"Fitting dynamic models to epidemic outbreaks with quantified uncertainty: A primer for parameter uncertainty, identifiability, and forecasts","volume":"2","year":"2017","journal-title":"Infect. Dis. Model"},{"key":"2026081011301899000_2026.07.22.26358639v2.32","doi-asserted-by":"crossref","unstructured":"MJ Keeling , P Rohani , Modeling Infectious Diseases in Humans and Animals. (Princenton University Press), (2007).","DOI":"10.1515\/9781400841035"},{"key":"2026081011301899000_2026.07.22.26358639v2.33","doi-asserted-by":"crossref","first-page":"e1005038","DOI":"10.1371\/journal.pmed.1005038","article-title":"Social contact patterns in the United Kingdom following the COVID-19 pandemic: The Reconnect cross-sectional survey","volume":"23","year":"2026","journal-title":"PLOS Medicine"},{"key":"2026081011301899000_2026.07.22.26358639v2.34","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0906910106"},{"key":"2026081011301899000_2026.07.22.26358639v2.35","doi-asserted-by":"crossref","first-page":"1754","DOI":"10.1093\/cid\/ciy876","article-title":"Vaccine Effectiveness Against Lineage-matched and -mismatched Influenza B Viruses Across 8 Seasons in Canada, 2010\u20132011 to 2017\u20132018","volume":"68","year":"2019","journal-title":"Clin. Infect. Dis"},{"key":"2026081011301899000_2026.07.22.26358639v2.36","doi-asserted-by":"crossref","first-page":"540","DOI":"10.1093\/cid\/ciac653","article-title":"Influenza During the 2010\u20132020 Decade in the United States: Seasonal Outbreaks and Vaccine Interventions","volume":"76","year":"2023","journal-title":"Clin. Infect. Dis"},{"key":"2026081011301899000_2026.07.22.26358639v2.37","doi-asserted-by":"publisher","DOI":"10.1126\/science.aag1322"},{"key":"2026081011301899000_2026.07.22.26358639v2.38","doi-asserted-by":"crossref","first-page":"833","DOI":"10.1097\/INF.0b013e31822db4dc","article-title":"Influenza B\/Victoria Antigen Induces Strong Recall of B\/Yamagata But Lower B\/Victoria Response in Children Primed With Two Doses of B\/Yamagata","volume":"30","year":"2011","journal-title":"The Pediatr. Infect. Dis. J"},{"key":"2026081011301899000_2026.07.22.26358639v2.39","doi-asserted-by":"crossref","first-page":"e0166107","DOI":"10.1371\/journal.pone.0166107","article-title":"Estimating the Lineage Dynamics of Human Influenza B Viruses","volume":"11","year":"2016","journal-title":"PLOS ONE"},{"key":"2026081011301899000_2026.07.22.26358639v2.40","doi-asserted-by":"publisher","DOI":"10.1016\/j.tpb.2003.10.002"},{"key":"2026081011301899000_2026.07.22.26358639v2.41","doi-asserted-by":"publisher","DOI":"10.1126\/science.1097211"},{"key":"2026081011301899000_2026.07.22.26358639v2.42","doi-asserted-by":"crossref","unstructured":"O Arhami , P Rohani , Topolow: A mapping algorithm for antigenic cross-reactivity and binding affinity assays. Bioinformatics p. btaf372 (2025).","DOI":"10.1101\/2025.02.09.637307"},{"key":"2026081011301899000_2026.07.22.26358639v2.43","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1016\/j.coisb.2021.03.005","article-title":"On structural and practical identifiability","volume":"25","year":"2021","journal-title":"Curr. Opin. Syst. Biol"},{"key":"2026081011301899000_2026.07.22.26358639v2.44","first-page":"14807","article-title":"Investigating a deterministic canonical model for tropical influenza","volume":"16","year":"2026","journal-title":"Sci. Reports"},{"key":"2026081011301899000_2026.07.22.26358639v2.45","doi-asserted-by":"publisher","DOI":"10.1371\/journal.ppat.1000647"},{"key":"2026081011301899000_2026.07.22.26358639v2.46","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pcbi.1009898"},{"key":"2026081011301899000_2026.07.22.26358639v2.47","first-page":"18079","article-title":"Explaining complex dynamical systems using conditional SHAP analysis with application to multi-variant epidemic dynamics","volume":"16","year":"2026","journal-title":"Sci. Reports"},{"key":"2026081011301899000_2026.07.22.26358639v2.48","doi-asserted-by":"crossref","first-page":"210530","DOI":"10.1098\/rsos.210530","article-title":"Vaccine escape in a heterogeneous population: insights for SARS-CoV-2 from a simple model","volume":"8","year":"2021","journal-title":"Royal Soc. Open Sci"},{"key":"2026081011301899000_2026.07.22.26358639v2.49","doi-asserted-by":"crossref","first-page":"111493","DOI":"10.1016\/j.jtbi.2023.111493","article-title":"The importance of vaccinated individuals to population-level evolution of pathogens","volume":"567","year":"2023","journal-title":"J. Theor. Biol"},{"key":"2026081011301899000_2026.07.22.26358639v2.50","doi-asserted-by":"crossref","first-page":"101136","DOI":"10.1016\/j.lanmic.2025.101136","article-title":"Duration of the serological response and effectiveness of the inactivated influenza vaccine in healthy adults aged 18\u201365 years: a systematic review and meta-analysis","volume":"6","year":"2025","journal-title":"The Lancet Microbe"},{"key":"2026081011301899000_2026.07.22.26358639v2.51","doi-asserted-by":"crossref","first-page":"e194","DOI":"10.1016\/S2666-5247(23)00319-1","article-title":"Laboratory-acquired infections and pathogen escapes worldwide between 2000 and 2021: a scoping review","volume":"5","year":"2024","journal-title":"The Lancet Microbe"},{"key":"2026081011301899000_2026.07.22.26358639v2.52","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMp2314801"},{"key":"2026081011301899000_2026.07.22.26358639v2.53","unstructured":"CDC (Centers for Disease Control and Prevention), NIH (National Institutes of Health), Biosafety in Microbiological and Biomedical Laboratories\u20146th Edition (2020)."},{"key":"2026081011301899000_2026.07.22.26358639v2.54","doi-asserted-by":"publisher","DOI":"10.1007\/s002850100120"},{"key":"2026081011301899000_2026.07.22.26358639v2.55","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.252512799"},{"key":"2026081011301899000_2026.07.22.26358639v2.56","doi-asserted-by":"publisher","DOI":"10.64898\/2026.08.03.26359614"},{"key":"2026081011301899000_2026.07.22.26358639v2.57","doi-asserted-by":"publisher","DOI":"10.1093\/aje\/kwm375"}],"container-title":[],"original-title":[],"link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.64898\/2026.07.22.26358639","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,11,6]],"date-time":"2026-11-06T23:00:13Z","timestamp":1794006013000},"score":1,"resource":{"primary":{"URL":"http:\/\/medrxiv.org\/lookup\/doi\/10.64898\/2026.07.22.26358639"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,23]]},"references-count":57,"URL":"https:\/\/doi.org\/10.64898\/2026.07.22.26358639","relation":{},"subject":[],"published":{"date-parts":[[2026,7,23]]},"subtype":"preprint"}}