{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T09:55:00Z","timestamp":1772272500089,"version":"3.50.1"},"reference-count":73,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,2,25]],"date-time":"2026-02-25T00:00:00Z","timestamp":1771977600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100023280","name":"CSL Seqirus","doi-asserted-by":"crossref","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}],"id":[{"id":"10.13039\/501100023280","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>This commentary provides an overview of the development of a zoonotic influenza vaccine, in response to the emergence of an H5N1 subtype virus from clade 2.3.4.4b in mid-2020. When development was initiated, the World Health Organization (WHO) had recommended four candidate vaccine viruses; the A\/Astrakhan\/3212\/2020-like strain was selected as it provided good coverage of circulating viruses and, critically, was available. To facilitate regulatory approval, the licence of an existing zoonotic vaccine, Aflunov (A\/turkey\/Turkey\/01\/2005)\u2014a pre-pandemic monovalent A\/H5N1 adjuvanted with MF59 and manufactured using the egg-based platform\u2014was duplicated, with the plan to submit a variation to the duplicate licence for the strain update. This was supported by a ferret immunogenicity study using pseudoviruses (allowing the work to be conducted at a lower biosafety level), in conjunction with clinical data from the original Aflunov licence application, and a US study (NCT05874713) on another candidate zoonotic vaccine manufactured using the cell-based platform. Qualification batches for characterisation studies were manufactured at-risk, until calibrated, homologous reagents were available, and the final product release and stability studies were conducted, with rolling provision of stability data to health authorities. The vaccine was initially approved with a shorter shelf-life, allowing early distribution in certain countries, with later extension of the shelf-life once data became available. In terms of procurement and logistics, early consultation between the European Commission and EU member states resulted in the award of a Framework Contract for the initial supply of 665,000 doses to 15 states. Learnings from the development of this vaccine may help to improve pandemic readiness in the future.<\/jats:p>","DOI":"10.3390\/vaccines14030203","type":"journal-article","created":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T09:31:32Z","timestamp":1772098292000},"page":"203","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The Road to Readiness: Commentary on the Journey of a Zoonotic H5 Influenza Vaccine Strain Update"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5239-2569","authenticated-orcid":false,"given":"Alexander T.","family":"Kennedy","sequence":"first","affiliation":[{"name":"Seqirus UK Ltd., Maidenhead SL6 8AD, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ray","family":"Longstaff","sequence":"additional","affiliation":[{"name":"Seqirus UK Ltd., Maidenhead SL6 8AD, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James","family":"Fitzpatrick","sequence":"additional","affiliation":[{"name":"Seqirus UK Ltd., Maidenhead SL6 8AD, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Clare","family":"Hughes","sequence":"additional","affiliation":[{"name":"Seqirus UK Ltd., Gaskill Road, Speke, Liverpool L24 9GR, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maria Teresa","family":"Malatesta","sequence":"additional","affiliation":[{"name":"Seqirus S.r.l., 53035 Siena, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Raffaella","family":"Brandi","sequence":"additional","affiliation":[{"name":"Seqirus S.r.l., 53035 Siena, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joanne","family":"Beighton","sequence":"additional","affiliation":[{"name":"Seqirus UK Ltd., Gaskill Road, Speke, Liverpool L24 9GR, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eve","family":"Versage","sequence":"additional","affiliation":[{"name":"Seqirus USA Inc., Waltham, MA 02451, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-6991-5511","authenticated-orcid":false,"given":"Nedzad","family":"Music","sequence":"additional","affiliation":[{"name":"Seqirus USA Inc., Waltham, MA 02451, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Howard","family":"Xu","sequence":"additional","affiliation":[{"name":"CSL Behring L.L.C., King of Prussia, PA 19406, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Monica","family":"Pagni","sequence":"additional","affiliation":[{"name":"Seqirus S.r.l., 53035 Siena, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Matthew","family":"Hohenboken","sequence":"additional","affiliation":[{"name":"Seqirus USA Inc., Waltham, MA 02451, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Beverly","family":"Taylor","sequence":"additional","affiliation":[{"name":"Seqirus UK Ltd., Gaskill Road, Speke, Liverpool L24 9GR, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4895","DOI":"10.1016\/j.vaccine.2010.05.031","article-title":"The 2009 A (H1N1) influenza virus pandemic: A review","volume":"28","author":"Girard","year":"2010","journal-title":"Vaccine"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"9","DOI":"10.3201\/eid1201.051254","article-title":"Influenza pandemics of the 20th century","volume":"12","author":"Kilbourne","year":"2006","journal-title":"Emerg. Infect. Dis."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"eadj2379","DOI":"10.1126\/scitranslmed.adj2379","article-title":"Many potential pathways to future pandemic influenza","volume":"15","author":"Morens","year":"2023","journal-title":"Sci. Transl. Med."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Rockman, S., Taylor, B., McCauley, J.W., Barr, I.G., Longstaff, R., and Bahra, R. (2022). Global Pandemic Preparedness: Optimizing Our Capabilities and the Influenza Experience. Vaccines, 10.","DOI":"10.3390\/vaccines10040589"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"398","DOI":"10.1016\/S1473-3099(23)00117-2","article-title":"Being ready for the next influenza pandemic?","volume":"23","author":"Kuiken","year":"2023","journal-title":"Lancet Infect. Dis."},{"key":"ref_6","unstructured":"World Health Organization (2025, December 01). Joint FAO\/WHO\/WOAH Preliminary Assessment of Recent Influenza A(H5N1) Viruses. Available online: https:\/\/www.who.int\/publications\/m\/item\/joint-fao-who-woah-preliminary-assessment-of-recent-influenza-a(h5n1)-viruses."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"e0042425","DOI":"10.1128\/jvi.00424-25","article-title":"Clade 2.3.4.4b highly pathogenic avian influenza H5N1 viruses: Knowns, unknowns, and challenges","volume":"99","author":"Xie","year":"2025","journal-title":"J. Virol."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Chrzastek, K., Lieber, C.M., and Plemper, R.K. (2025). H5N1 Clade 2.3.4.4b: Evolution, Global Spread, and Host Range Expansion. Pathogens, 14.","DOI":"10.3390\/pathogens14090929"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e0398924","DOI":"10.1128\/mbio.03989-24","article-title":"Clade 2.3.4.4b H5N1 neuraminidase has a long stalk, which is in contrast to most highly pathogenic H5N1 viruses circulating between 2002 and 2020","volume":"16","author":"Hermann","year":"2025","journal-title":"mBio"},{"key":"ref_10","unstructured":"Pan American Health Organization (2025, December 01). Epidemiological Update Avian Influenza A(H5N1) in the Americas Region. Available online: https:\/\/www.paho.org\/sites\/default\/files\/2025-03\/2025-mar-4-phe-epidupdate-avianinfluenza-eng-final.pdf."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"533","DOI":"10.1093\/infdis\/jiae379","article-title":"An Update on Highly Pathogenic Avian Influenza A(H5N1) Virus, Clade 2.3.4.4b","volume":"230","author":"Webby","year":"2024","journal-title":"J. Infect. Dis."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"967","DOI":"10.3201\/eid2605.190994","article-title":"Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings\u2014Personal Protective and Environmental Measures","volume":"26","author":"Xiao","year":"2020","journal-title":"Emerg. Infect. Dis."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"976","DOI":"10.3201\/eid2605.190995","article-title":"Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings\u2014Social Distancing Measures","volume":"26","author":"Fong","year":"2020","journal-title":"Emerg. Infect. Dis."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"S309","DOI":"10.1093\/infdis\/jiaf264","article-title":"Optimizing Antiviral Stockpiles for Pandemic Response: A Strategic Framework","volume":"232","author":"Bright","year":"2025","journal-title":"J. Infect. Dis."},{"key":"ref_15","unstructured":"European Medicines Agency (2025, December 01). Guideline On Dossier Structure and Content for Pandemic Influenza Vaccine Marketing Authorisation Application (Revision). Available online: https:\/\/www.ema.europa.eu\/en\/documents\/scientific-guideline\/guideline-dossier-structure-and-content-pandemic-influenza-vaccine-marketing-authorisation-application-revision-superseded_en.pdf."},{"key":"ref_16","unstructured":"European Medicines Agency (2025, December 01). Influenza Vaccines\u2014Submission and Procedural Requirements\u2014Scientific Guideline. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/scientific-guideline\/guideline-influenza-vaccines-submission-and-procedural-requirements-rev2_en.pdf."},{"key":"ref_17","unstructured":"World Health Organization (2025, December 01). Global Influenza Surveillance and Response System (GISRS). Available online: https:\/\/www.who.int\/initiatives\/global-influenza-surveillance-and-response-system."},{"key":"ref_18","unstructured":"World Health Organization (2025, December 01). Recommendations Announced for Influenza Vaccine Composition for the 2024\u20132025 Northern Hemisphere Influenza Season. Available online: https:\/\/www.who.int\/news\/item\/23-02-2024-recommendations-announced-for-influenza-vaccine-composition-for-the-2024-2025-northern-hemisphere-influenza-season."},{"key":"ref_19","unstructured":"World Health Organization (2025, December 01). Genetic and Antigenic Characteristics of Zoonotic Influenza a Viruses and Development of Candidate Vaccine Viruses for Pandemic Preparedness. Available online: https:\/\/cdn.who.int\/media\/docs\/default-source\/influenza\/who-influenza-recommendations\/vcm-sh-2025\/c.-26-september-2025-antigenic-and-genetic-characteristics-of-zoonotic-influenza-a-viruses-and-development-of-candidate-vaccine-viruses-for-pandemic-preparedness.pdf."},{"key":"ref_20","unstructured":"European Medicines Agency (2024, December 01). Aflunov Summary of Product Characteristics. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/product-information\/aflunov-epar-product-information_en.pdf."},{"key":"ref_21","unstructured":"European Medicines Agency (2025, December 01). Incellipan Summary of Product Characteristics. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/product-information\/incellipan-epar-product-information_en.pdf."},{"key":"ref_22","unstructured":"European Medicines Agency (2025, December 01). Adjupanrix Summary of Product Characteristics. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/product-information\/adjupanrix-epar-product-information_en.pdf."},{"key":"ref_23","unstructured":"European Medicines Agency (2025, December 01). Foclivia Summary of Product Characteristics. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/product-information\/foclivia-epar-product-information_en.pdf."},{"key":"ref_24","unstructured":"European Medicines Agency (2025, December 01). Assessment Report: Celldemic. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/assessment-report\/celldemic-epar-public-assessment-report_en.pdf."},{"key":"ref_25","unstructured":"European Medicines Agency (2026, January 09). Zoonotic Influenza Vaccine Seqirus\u2014Authorization. Available online: https:\/\/www.ema.europa.eu\/en\/medicines\/human\/EPAR\/zoonotic-influenza-vaccine-seqirus#authorisation-details."},{"key":"ref_26","unstructured":"Food and Drug Administration (2025, December 01). Audenz Prescribing Information, Available online: https:\/\/www.fda.gov\/files\/vaccines%2C%20blood%20%26%20biologics\/published\/Package-Insert-AUDENZ_2.pdf."},{"key":"ref_27","unstructured":"GlaxoSmithKline (2026, January 09). H5N1 Vaccine Approved by the U.S. FDA as Pandemic Influenza Preparedness Measure. Available online: https:\/\/www.gsk.com\/en-gb\/media\/press-releases\/h5n1-vaccine-approved-by-the-us-fda-as-pandemic-influenza-preparedness-measure."},{"key":"ref_28","unstructured":"U.S. Department of Health and Human Services Food and Drug Administration (2026, January 09). Sanofi Influenza Virus Vaccine\u2014US FDA Prescribing Information, Available online: https:\/\/www.fda.gov\/media\/74534\/download."},{"key":"ref_29","unstructured":"European Medicines Agency (2026, January 09). Type II Variation Assessment Report. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/variation-report\/zoonotic-influenza-vaccine-seqirus-h-c-006375-ii-0001-epar-assessment-report-variation_en.pdf."},{"key":"ref_30","unstructured":"World Health Organization (2026, January 09). Recommended Composition of Influenza Virus Vaccines for Use in the 2024\u20132025 Northern Hemisphere Influenza Season. Available online: https:\/\/www.who.int\/publications\/m\/item\/recommended-composition-of-influenza-virus-vaccines-for-use-in-the-2024-2025-northern-hemisphere-influenza-season."},{"key":"ref_31","unstructured":"World Health Organization (2025, December 01). Pandemic Influenza Preparedness Framework for the Sharing of Influenza Viruses and Access to Vaccines and Other Benefits. Available online: https:\/\/iris.who.int\/server\/api\/core\/bitstreams\/4e22d25c-7084-4832-a0ff-667eac7ed714\/content."},{"key":"ref_32","unstructured":"Convention on Biological Diversity (2025, December 01). Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from Their Utilization to the Convention on Biological Diversity. Available online: https:\/\/www.cbd.int\/abs\/doc\/protocol\/nagoya-protocol-en.pdf."},{"key":"ref_33","unstructured":"World Health Organization (2025, December 01). Genetic and Antigenic Characteristics of Zoonotic Influenza a Viruses and Development of Candidate Vaccine Viruses for Pandemic Preparedness. Available online: https:\/\/cdn.who.int\/media\/docs\/default-source\/influenza\/who-influenza-recommendations\/vcm-northern-hemisphere-recommendation-2023-2024\/20230224_zoonotic_recommendations.pdf?sfvrsn=38c739fa_4."},{"key":"ref_34","unstructured":"World Health Organization (2025, December 01). Summary of Status of Development and Availability of A(H5) non\u2013A(H5N1) Candidate Vaccine Viruses and Potency Testing Reagents. Available online: https:\/\/cdn.who.int\/media\/docs\/default-source\/influenza\/cvvs\/cvv-zoonotic-northern-hemisphere-2025-2026\/h5-non-h5n1_cvv_-20250228_20250813.pdf?sfvrsn=273530c8_7."},{"key":"ref_35","unstructured":"World Health Organization (2025, December 01). Summary of Status of Development and Availability of A(H5N1) Candidate Vaccine Viruses and Potency Testing Reagents. Available online: https:\/\/cdn.who.int\/media\/docs\/default-source\/influenza\/cvvs\/cvv-zoonotic-northern-hemisphere-2025-2026\/h5n1_summary_a_h5n1_cvv_20250228_rev20250813.pdf?sfvrsn=9c99e0a4_8."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"981","DOI":"10.1016\/j.virs.2024.11.005","article-title":"Pandemic preparedness of effective vaccines for the outbreak of newly H5N1 highly pathogenic avian influenza virus","volume":"39","author":"Gao","year":"2024","journal-title":"Virol. Sin."},{"key":"ref_37","unstructured":"Davis, T. (2025, December 01). Highly Pathogenic Avian Influenza A(H5Nx) Virus Surveillance and Characterization in the United States and Globally and Recommendations for Candidate Vaccine Virus Development, Available online: https:\/\/www.fda.gov\/media\/182596\/download."},{"key":"ref_38","unstructured":"European Medicines Agency (2026, January 09). Assessment Report: Zoonotic Influenza Vaccine Seqirus. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/assessment-report\/zoonotic-influenza-vaccine-seqirus-epar-public-assessment-report_en.pdf."},{"key":"ref_39","unstructured":"World Health Organization (2025, December 01). Antigenic and Genetic Characteristics of Zoonotic Influenza Viruses and Development of Candidate Vaccine Viruses for Pandemic Preparedness. Available online: https:\/\/cdn.who.int\/media\/docs\/default-source\/influenza\/who-influenza-recommendations\/vcm-northern-hemisphere-recommendation-2018-2019\/201802-zoonotic-vaccinevirusupdate.pdf."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"2400063","DOI":"10.2807\/1560-7917.ES.2024.29.25.2400063","article-title":"Highly pathogenic avian influenza A(H5N1) virus infections on fur farms connected to mass mortalities of black-headed gulls, Finland, July to October 2023","volume":"29","author":"Kareinen","year":"2024","journal-title":"Eurosurveillance"},{"key":"ref_41","first-page":"2300366","article-title":"Outbreak of highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus in cats, Poland, June to July 2023","volume":"28","author":"Monne","year":"2023","journal-title":"Eurosurveillance"},{"key":"ref_42","first-page":"2300001","article-title":"Highly pathogenic avian influenza A(H5N1) virus infection in farmed minks, Spain, October 2022","volume":"28","author":"Monne","year":"2023","journal-title":"Eurosurveillance"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"104827","DOI":"10.1016\/j.ebiom.2023.104827","article-title":"Characterization of highly pathogenic clade 2.3.4.4b H5N1 mink influenza viruses","volume":"97","author":"Maemura","year":"2023","journal-title":"EBioMedicine"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"e2257810","DOI":"10.1080\/22221751.2023.2257810","article-title":"Highly pathogenic avian influenza A virus (HPAIV) H5N1 infection in two European grey seals (Halichoerus grypus) with encephalitis","volume":"12","author":"Mirolo","year":"2023","journal-title":"Emerg. Microbes Infect."},{"key":"ref_45","unstructured":"World Health Organization (2025, December 01). Global Influenza Programme. Available online: https:\/\/www.who.int\/teams\/global-influenza-programme\/vaccines\/who-recommendations."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"539","DOI":"10.4161\/hv.7.5.14821","article-title":"Passive surveillance of adverse events of an MF59-adjuvanted H1N1v vaccine during the pandemic mass vaccinations","volume":"7","author":"Banzhoff","year":"2011","journal-title":"Hum. Vaccines"},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Jelinek, T., Schwarz, T.F., Reisinger, E., Malfertheiner, P., Versage, E., Van Twuijver, E., and Hohenboken, M. (2024). Safety, Tolerability, and Immunogenicity of aH5N1 Vaccine in Adults with and without Underlying Medical Conditions. Vaccines, 12.","DOI":"10.3390\/vaccines12050481"},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Malfertheiner, P., Versage, E., Van Twuijver, E., Rizzardini, G., and Hohenboken, M. (2025). Safety, Tolerability, and Immunogenicity of aH5N1 Vaccine in Adults with and Without Underlying Immunosuppressive Conditions. Vaccines, 13.","DOI":"10.3390\/vaccines13040379"},{"key":"ref_49","unstructured":"ClinicalTrials.gov (2025, December 01). BARDA BP-I-23-001 H5 Influenza, Available online: https:\/\/clinicaltrials.gov\/study\/NCT06560151."},{"key":"ref_50","unstructured":"CSL Sequirus (2025, December 01). CSL Seqirus Announces U.S. Government Award to Manufacture and Clinically Assess Influenza A(H5N8) Pre-Pandemic Vaccine. Available online: https:\/\/www.cslseqirus.us\/news\/csl-seqirus-us-government-award-to-manufacture-and-assess-influenza-a-h5n8-pre-pandemic-vaccine."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"575","DOI":"10.1242\/dmm.007823","article-title":"The ferret as a model organism to study influenza A virus infection","volume":"4","author":"Belser","year":"2011","journal-title":"Dis. Model. Mech."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"e01113-18","DOI":"10.1128\/mBio.01113-18","article-title":"Moving Forward: Recent Developments for the Ferret Biomedical Research Model","volume":"9","author":"Albrecht","year":"2018","journal-title":"mBio"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"228","DOI":"10.1128\/CVI.00604-15","article-title":"Correlates of Protection against Influenza in the Elderly: Results from an Influenza Vaccine Efficacy Trial","volume":"23","author":"Dunning","year":"2016","journal-title":"Clin. Vaccine Immunol."},{"key":"ref_54","doi-asserted-by":"crossref","unstructured":"Coudeville, L., Bailleux, F., Riche, B., Megas, F., Andre, P., and Ecochard, R. (2010). Relationship between haemagglutination-inhibiting antibody titres and clinical protection against influenza: Development and application of a bayesian random-effects model. BMC Med. Res. Methodol., 10.","DOI":"10.1186\/1471-2288-10-18"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"767","DOI":"10.1017\/S0022172400022610","article-title":"The role of serum haemagglutination-inhibiting antibody in protection against challenge infection with influenza A2 and B viruses","volume":"70","author":"Hobson","year":"1972","journal-title":"Epidemiol. Infect."},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Gilbert, P.B., Fong, Y., Juraska, M., Carpp, L.N., Monto, A.S., Martin, E.T., and Petrie, J.G. (2019). HAI and NAI titer correlates of inactivated and live attenuated influenza vaccine efficacy. BMC Infect. Dis., 19.","DOI":"10.1186\/s12879-019-4049-5"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"ofab477","DOI":"10.1093\/ofid\/ofab477","article-title":"Association Between Hemagglutination Inhibition Antibody Titers and Protection Against Reverse-Transcription Polymerase Chain Reaction\u2013Confirmed Influenza Illness in Children 6\u201335 Months of Age: Statistical Evaluation of a Correlate of Protection","volume":"9","author":"Danier","year":"2021","journal-title":"Open Forum Infect. Dis."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"srep44727","DOI":"10.1038\/srep44727","article-title":"The immune correlates of protection for an avian influenza H5N1 vaccine in the ferret model using oil-in-water adjuvants","volume":"7","author":"Wong","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_59","doi-asserted-by":"crossref","unstructured":"Suguitan, A.L., McAuliffe, J., Mills, K.L., Jin, H., Duke, G., Lu, B., Luke, C.J., Murphy, B., Swayne, D.E., and Kemble, G. (2006). Live, Attenuated Influenza A H5N1 Candidate Vaccines Provide Broad Cross-Protection in Mice and Ferrets. PLoS Med., 3.","DOI":"10.1371\/journal.pmed.0030360"},{"key":"ref_60","unstructured":"European Medicines Agency (2025, December 01). Guideline on Influenza Vaccines (Non-Clinical and Clinical Module). Available online: https:\/\/www.ema.europa.eu\/en\/documents\/scientific-guideline\/influenza-vaccines-non-clinical-and-clinical-module_en.pdf."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/j.ajpath.2019.09.017","article-title":"A Guide for the Use of the Ferret Model for Influenza Virus Infection","volume":"190","author":"Belser","year":"2020","journal-title":"Am. J. Pathol."},{"key":"ref_62","unstructured":"U.S. Department of Health and Human Services Food and Drug Administration (2026, January 09). Guidance for Industry Clinical Data Needed to Support the Licensure of Pandemic Influenza Vaccines, Available online: https:\/\/www.fda.gov\/files\/vaccines,%20blood%20&%20biologics\/published\/Guidance-for-Industry--Clinical-Data-Needed-to-Support-the-Licensure-of-Pandemic-Influenza-Vaccines.pdf."},{"key":"ref_63","unstructured":"Segovia, K., Rathnasinghe, R., Patton, C., Kwon, B., Longstaff, R.A., Hofmann, D., Banger, K.K., Xu, H., Lacey, M., and Settembre, E. (2026). MF59-Adjuvanted A\/Astrakhan Influenza Vaccine Induces Cross-Neutralizing H5N1 Antibodies in Ferrets Against Circulating Clade 2.3.4.4b Viruses, CSL Seqirus. manuscript submitted."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"174","DOI":"10.1080\/14760584.2023.2299380","article-title":"Pseudoviruses, a safer toolbox for vaccine development against enveloped viruses","volume":"23","author":"Thimmiraju","year":"2024","journal-title":"Expert Rev. Vaccines"},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1038\/s41564-025-02183-5","article-title":"Influenza A(H5N8) vaccine induces humoral and cell-mediated immunity against highly pathogenic avian influenza clade 2.3.4.4b A(H5N1) viruses in at-risk individuals","volume":"11","author":"Liedes","year":"2025","journal-title":"Nat. Microbiol."},{"key":"ref_66","doi-asserted-by":"crossref","unstructured":"Wadey, C., and Rockman, S. (2024). Analysing the Potency of a Seasonal Influenza Vaccine Using Reference Antisera from Heterologous Strains. Vaccines, 12.","DOI":"10.3390\/vaccines12060596"},{"key":"ref_67","unstructured":"European Commission (2025, December 01). Commission Secures Access to 665,000 Doses of Zoonotic Influenza Vaccines. Available online: https:\/\/health.ec.europa.eu\/latest-updates\/commission-secures-access-665000-doses-zoonotic-influenza-vaccines-2024-06-11_en."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"512","DOI":"10.1016\/j.vaccine.2020.12.018","article-title":"Global production capacity of seasonal and pandemic influenza vaccines in 2019","volume":"39","author":"Sparrow","year":"2021","journal-title":"Vaccine"},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"90","DOI":"10.3390\/vaccines3010090","article-title":"Assaying the Potency of Influenza Vaccines","volume":"3","author":"Minor","year":"2015","journal-title":"Vaccines"},{"key":"ref_70","unstructured":"European Court of Auditors (2025, December 01). EU COVID-19 Vaccine Procurement. Available online: https:\/\/www.eca.europa.eu\/Lists\/ECADocuments\/SR22_19\/SR_EU_COVID_vaccine_procurement_EN.pdf."},{"key":"ref_71","unstructured":"UK Health Security Agency (2026, January 09). UK Secures H5 Influenza Vaccine to Boost Pandemic Preparedness, Available online: https:\/\/www.gov.uk\/government\/news\/uk-secures-h5-influenza-vaccine-to-boost-pandemic-preparedness."},{"key":"ref_72","unstructured":"European Medicines Agency (2025, December 09). Zoonotic Influenza Vaccine Seqirus\u2014Procedural Steps Taken and Scientific Information After the Authorisation. Available online: https:\/\/www.ema.europa.eu\/en\/documents\/procedural-steps-after\/zoonotic-influenza-vaccine-seqirus-epar-procedural-steps-taken-scientific-information-after-authorisation-archive_en.pdf?utm."},{"key":"ref_73","unstructured":"CSL Seqirus (2026, January 09). CSL Seqirus Announces Third U.S. Government Award in Relation to Influenza A(H5N8) Candidate Vaccine. Available online: https:\/\/www.prnewswire.com\/news-releases\/csl-seqirus-announces-third-us-government-award-in-relation-to-influenza-ah5n8-candidate-vaccine-301911153.html."}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/3\/203\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T05:14:35Z","timestamp":1772255675000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/3\/203"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,25]]},"references-count":73,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["vaccines14030203"],"URL":"https:\/\/doi.org\/10.3390\/vaccines14030203","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,25]]}}}