Avian Influenza A(H9N2) Virus Transmission across Chicken Production and Distribution Networks, Vietnam

Mathew Hennessey; Thuy Hoang Thi; Jayna Raghwani; Younjung Kim; Hoa Thi Thanh Pham; Trang Huyen Nguyen; Hung Quoc Nguyen; Joshua G. Lynton-Jenkins; Ashley C. Banyard; Ian H. Brown; Joe James; Tom Lewis; Nicola S. Lewis; Dirk Pfeiffer; Fiona Tomley; Damer Blake; Ngoc Pham Thi; Anne Conan; Vuong Nghia Bui; Guillaume Fournié

doi:10.3201/eid3202.251416

Avian Influenza A(H9N2) Virus Transmission across Chicken Production and Distribution Networks, Vietnam

Mathew Hennessey^*, Thuy Hoang Thi, Jayna Raghwani, Younjung Kim, Hoa Thi Thanh Pham, Trang Huyen Nguyen, Hung Quoc Nguyen, Joshua G. Lynton-Jenkins, Ashley C. Banyard, Ian H. Brown, Joe James, Tom Lewis, Nicola S. Lewis, Dirk Pfeiffer, Fiona Tomley, Damer Blake, Ngoc Pham Thi, Anne Conan, Vuong Nghia Bui (Co-last Author), Guillaume Fournié (Co-last Author)

^*Corresponding author for this work

Centre for Applied One Health Research and Policy Advice

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

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Abstract

In northern Vietnam, during March 2021–March 2022, prevalence of influenza A(H9N2) in chickens was higher in distribution facilities than on farms and varied between facility types. Phylogenetic analysis indicated extensive viral mixing along networks of chicken production and distribution, highlighting a need for risk mitigation across the entire network. © 2026 by the Centers for Disease Control and Prevention. All rights reserved.

Original language	English
Pages (from-to)	259-264
Number of pages	6
Journal	Emerging Infectious Diseases
Volume	32
Issue number	2
Online published	12 Feb 2026
DOIs	https://doi.org/10.3201/eid3202.251416
Publication status	Published - Feb 2026

Bibliographical note

Full text of this publication does not contain sufficient affiliation information. Research Unit(s) information for this record is based on his previous affiliation.

Funding

We thank Saira Butt for support in the initial development of the Bayesian model, the Food and Agricultural Organization and the Vietnamese Department for Animal Health for sharing information about the locations of markets and slaughter facilities, and the numerous participants for giving up their time to take part in this study.Financial support for this study was obtained through the United Kingdom Research and Innovation Global Challenge Research Fund One Health Poultry Hub (grant no. BB/S011269/1) awarded to the Royal Veterinary College, 1 of 12 interdisciplinary research hubs funded under the UK government's Global Challenges Research Fund Interdisciplinary Research Hub initiative. G.F. is supported by the French National Research Agency and the French Ministry of Higher Education and Research. Animal and Plant Health Agency staff were funded by the UK Department for the Environment, Food and Rural Affairs and the devolved Scottish and Welsh governments (grant nos. SE2213, SE2227, and SV3006).

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 3 Good Health and Well-being

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Hennessey, M., Hoang Thi, T., Raghwani, J., Kim, Y., Pham, H. T. T., Nguyen, T. H., Nguyen, H. Q., Lynton-Jenkins, J. G., Banyard, A. C., Brown, I. H., James, J., Lewis, T., Lewis, N. S., Pfeiffer, D., Tomley, F., Blake, D., Thi, N. P., Conan, A., Bui, V. N., & Fournié, G. (2026). Avian Influenza A(H9N2) Virus Transmission across Chicken Production and Distribution Networks, Vietnam. Emerging Infectious Diseases, 32(2), 259-264. https://doi.org/10.3201/eid3202.251416

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author = "Mathew Hennessey and {Hoang Thi}, Thuy and Jayna Raghwani and Younjung Kim and Pham, {Hoa Thi Thanh} and Nguyen, {Trang Huyen} and Nguyen, {Hung Quoc} and Lynton-Jenkins, {Joshua G.} and Banyard, {Ashley C.} and Brown, {Ian H.} and Joe James and Tom Lewis and Lewis, {Nicola S.} and Dirk Pfeiffer and Fiona Tomley and Damer Blake and Thi, {Ngoc Pham} and Anne Conan and Bui, {Vuong Nghia} and Guillaume Fourni{\'e}",

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year = "2026",

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doi = "10.3201/eid3202.251416",

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Hennessey, M, Hoang Thi, T, Raghwani, J, Kim, Y, Pham, HTT, Nguyen, TH, Nguyen, HQ, Lynton-Jenkins, JG, Banyard, AC, Brown, IH, James, J, Lewis, T, Lewis, NS, Pfeiffer, D, Tomley, F, Blake, D, Thi, NP, Conan, A, Bui, VN & Fournié, G 2026, 'Avian Influenza A(H9N2) Virus Transmission across Chicken Production and Distribution Networks, Vietnam', Emerging Infectious Diseases, vol. 32, no. 2, pp. 259-264. https://doi.org/10.3201/eid3202.251416

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AU - Pham, Hoa Thi Thanh

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AU - Brown, Ian H.

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AU - Lewis, Nicola S.

AU - Pfeiffer, Dirk

AU - Tomley, Fiona

AU - Blake, Damer

AU - Thi, Ngoc Pham

AU - Conan, Anne

AU - Bui, Vuong Nghia

AU - Fournié, Guillaume

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N2 - In northern Vietnam, during March 2021–March 2022, prevalence of influenza A(H9N2) in chickens was higher in distribution facilities than on farms and varied between facility types. Phylogenetic analysis indicated extensive viral mixing along networks of chicken production and distribution, highlighting a need for risk mitigation across the entire network. © 2026 by the Centers for Disease Control and Prevention. All rights reserved.

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Avian Influenza A(H9N2) Virus Transmission across Chicken Production and Distribution Networks, Vietnam

Abstract

Bibliographical note

Funding

UN SDGs

Publisher's Copyright Statement

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