H7N9 refers to avian influenza A viruses of the H7 hemagglutinin subtype that can infect humans and pose a pandemic threat [1][2]. The H7N9 viruses emerged in humans in 2013 and were subsequently nearly eliminated in China [1].
Disease overview
Evidence-backed information EN 5/7 applicable sections · ZH 5/7 applicable sections Updated Oct 23, 2026
Avian H7N9 influenza viruses represent a potential pandemic threat to global public health and have caused severe human infection with high mortality [1][2]. China nearly eliminated the pervasive H7N9 viruses that emerged in 2013 through a cull-plus-vaccination strategy [1]. Adjuvanted H7N9 vaccines may be the optimal available option in a pandemic setting [2].
Read the full clinical and epidemiological profile 6
H7N9 infection in humans is severe and associated with high mortality [2]. The viruses have caused severe infection in affected individuals [1][2].
H7N9 viruses emerged in humans in 2013 and were nearly eliminated in China through public health interventions [1]. Globally, H5 and H7 subtype avian influenza viruses combined have caused 2634 human cases with over 1000 deaths [1].
H5 influenza viruses are spread by migratory wild birds and have caused three waves of influenza outbreaks across multiple continents, with the third wave that started in 2020 being ongoing [1].
China adopted a cull-plus-vaccination strategy that nearly eliminated H7N9 viruses and limited poultry losses [1]. Clinical trials of H7N9 vaccines show that non-adjuvanted high-dose formulations yield limited immunogenicity and more adverse events, whereas adjuvanted formulations improve immune responses and may be the optimal pandemic option [2]. Among adjuvants, aluminium showed safety advantages while non-aluminium adjuvants saved vaccine dose [2].
- 1 Shi J et al. Alarming situation of emerging H5 and H7 avian influenza and effective control strategies. Emerg Microbes Infect. 2023 Dec. PMID: 36458831. doi: 10.1080/22221751.2022.2155072. PubMed: https://pubmed.ncbi.nlm.nih.gov/36458831/
- 2 Zheng D et al. Comparative effectiveness of H7N9 vaccines in healthy individuals. Hum Vaccin Immunother. 2019. PMID: 30148691. doi: 10.1080/21645515.2018.1515454. PubMed: https://pubmed.ncbi.nlm.nih.gov/30148691/
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- 1E30.0
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Based on the MaxEnt model the analysis of influencing factors and simulation of potential risk areas of human infection with avian influenza A (H7N9) in China.
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Alarming situation of emerging H5 and H7 avian influenza and effective control strategies
Emerging Microbes & Infections
Showing 5 of 27 related publications.
Literature links are provided for discovery and do not alter or validate the surveillance series above.
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