A Systematic Review and Meta-Analysis of the Seroprevalence of Influenza A(H9N2) Infection Among Humans
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INTRODUCTION: Given that influenza A(H9N2) is recognized as a pandemic threat, we evaluated the overall burden of influenza A(H9N2) infections among avian-exposed human populations. METHODS: We performed a systematic search of PubMed, AGRICOLA, and CAB Abstracts databases for literature published during 1997-2013. Studies reporting serological evidence of human influenza A(H9N2) infection among avian-exposed populations were included. We used a World Health Organization (WHO)-recommended case definition for serological evidence of infection based on results of hemagglutination inhibition (HI) and microneutralization (MN) assays. We calculated overall seroprevalence through a random effects meta-analysis model. RESULTS: Seroprevalence data reported by the studies ranged from 1% to 43% (median, 9%) by HI, which was not significantly different from the seroprevalence estimated through the WHO-recommended case definition (median, 1.3%; range, 0.5%-42.6%). Reported seroprevalence by MN ranged from 0.6% to 9% (median, 2.7%), which was greater than the seroprevalence estimated through the WHO-recommended case definition (median, 0.3%; range, 0.1%-1.4%). CONCLUSIONS: A small proportion of avian-exposed humans had evidence of influenza A(H9N2) infection. As the virus has a near global distribution in poultry, it seems likely that present surveillance efforts are missing mild or asymptomatic infections among avian-exposed persons. It seems prudent to closely monitor avian-exposed populations for influenza A(H9N2) infection to provide prepandemic warnings.
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Given the rarity of H9, H6 and H10 human infections, the binding antibodies likely represent heterosubtypic immunity elicited by vaccination or exposure to other influenza A subtypes.
“Given the rarity of H9, H6 and H10 human infections23–25 it is likely the binding antibodies represent heterosubtypic immunity elicited by vaccination or exposure to other influenza A subtypes.”
From Clade 2.3.4.4b but not historical clade 1 HA replicating RNA vaccine protects against bovine H5N1 challenge in mice (2025) · cites this paper as [23]
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Research works printed but not linked: 2
- Liu Xing Bing Xue Za Zhi 2009; 30:1111-3.
- Influenza A(H9N2) in Humans: Systematic Review • JID 2015:212 (15 August) • 569 Downloaded from https://academic.oup.com/jid/article/212/4/562/820084 by guest on 30 August 2023
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Hawman, D. W., Tipih, T., Hodge, E., Stone, E. T., Warner, N., McCarthy, N., Granger, B., Meade-White, K., Leventhal, S., Hatzakis, K., et al. (2025) · Nature Communications · doi:10.1038/s41467-024-55546-7 · Cited by 20 · see citing works
- Authors
- Khan, S. U., Anderson, B. D., Heil, G. L., Liang, S., & Gray, G. C.
- Affiliations
- University of Florida Health (US)
- National University of Singapore (SG)
- Corresponding author
- Khan, Salah Uddin
- Venue
- Journal of Infectious Diseases
- Publisher
- Oxford University Press (OUP)
- Published
- 2015-02-23
- Volume
- 212
- Issue
- 4
- Pages
- 562-569
- ISSN
- 0022-1899 (ISSN-L)
- 1537-6613
- PMC
- PMC4598807
- OpenAlex
- W2168554389
- Cited by
- 88
- References
- 53
- Citations by year
- 2026: 2 · 2025: 5 · 2024: 4 · 2023: 4 · 2022: 3 · 2021: 9 · 2020: 12 · 2019: 12 · 2018: 14 · 2017: 13 · 2016: 7 · 2015: 3
- FWCI
- 1.60
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- The Journal of Infectious Diseases (publishedVersion)
- Europe PMC (PubMed Central) (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- U.S. Department of Defense
- National Institute of Allergy and Infectious Diseases (R01AI108993)
- Topics
- Health Sciences › Medicine › Epidemiology › Influenza Virus Research Studies
- Health Sciences › Medicine › Epidemiology › Virology and Viral Diseases
- Health Sciences › Medicine › Epidemiology › Respiratory viral infections research
- Keywords
- seroprevalence, human influenza infection, hemagglutination inhibition test, microneutralization, WHO case definition, asymptomatic infection, pandemic preparedness, surveillance (medicine)
- MeSH terms
- Animals, Antibodies, Viral, Humans, Influenza, Human, Zoonoses, Seroepidemiologic Studies, Influenza A Virus, H9N2 Subtype
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