Influenza A H7 viruses are a group of influenza viruses that normally circulate among birds. The influenza A(H7N9) virus is one subgroup among the larger group of H7 viruses. Although some H7 viruses (H7N2, H7N3 and H7N7) have occasionally been found to infect humans, no human infections with H7N9 viruses have been reported until March 2013, when three urban residents of Shanghai or Anhui, China, presented with rapidly progressing lower respiratory tract infections and were found to be infected with a novel reassortant avian-origin influenza A (H7N9) virus.

Developing a vaccine

There is currently no vaccine for the prevention of avian influenza A(H7N9) infections although at least four biopharmaceutical companies have candidates that are being tested in animal and human trials.

Wu YL, Shen L-W, Ding Y-P. Preliminary success in the characterization and management of a sudden breakout of a novel H7N9 influenza A virus. International Journal of Biological Sciences, 2014, volume 10, number 1, pages 109-118. Full text

Bart SA. et al. A Cell Culture–Derived MF59-Adjuvanted Pandemic A/H7N9 Vaccine Is Immunogenic in Adults. Sci Transl Med 30 April 2014: Vol. 6, Issue 234, p. 234ra55. Full text

General Resources

WHO - Avian influenza A(H7N9) virus
WHO - Avian Influenza A(H7N9) Response:An Investment in Public Health Preparedness
Hong Kong Centre for Health Protection (CHP) - Avian influenza
CHP - Weekly avian influenza report
Chinese Center for Disease Control and Prevention (CCDCP)- H7N9 Weekly Updates
Frequently asked questions
Research highlights

H7N9 Avian Influenza - Recent Journal Articles


Feng L, et al. Burden of influenza-associated outpatient influenza-like illness consultations in China, 2006-2015: A population-based study. Influenza Other Respir Viruses. 2019 Dec 23. Full Text

Gao S, et al. Identification of a Type-Specific Promoter Element That Differentiates between Influenza A and B Viruses. J Virol. 2019 Nov 13;93(23). pii: e01164-19. Full Text

Li J, et al. Rapid isolation of a potent human antibody against H7N9 influenza virus from an infected patient. Antiviral Res. 2019 Oct;170:104564. Full Text

Li YT, et al. Avian influenza viruses in humans: lessons from past outbreaks. Br Med Bull. 2019 Dec 14. pii: ldz036. Full Text

Lim VW, et al. Passive immune therapy and other immunomodulatory agents for the treatment of severe influenza: Systematic review and meta-analysis. Influenza Other Respir Viruses. 2019 Nov 16. Full Text

Martinez L, et al. A Risk Classification Model to Predict Mortality Among Laboratory-Confirmed Avian Influenza A H7N9 Patients: A Population-Based Observational Cohort Study. J Infect Dis. 2019 Oct 22;220(11):1780-1789. Full Text

Wu X, Xiao L, Li L. Research progress on human infection with avian influenza H7N9. Front Med. 2020 Jan 23. Full text

Yang Y, et al. Clinical and virological characteristics of human infections with H7N9 avian influenza virus in Shenzhen, China, 2013-2017. J Infect. 2019 Oct;79(4):389-399. Full Text




Avian influenza (AI), commonly called bird flu, is an infectious viral disease of birds.

Most avian influenza viruses do not infect humans.  Some, such as H5N1, have caused serious infections in people.  Outbreaks of AI in poultry may raise global public health concerns due to their effect on poultry populations, their potential to cause serious disease in people, and their pandemic potential.

Reports of highly pathogenic AI epidemics in poultry can seriously impact local and global economies and international trade.

The majority of human cases of H5N1 infection have been associated with direct or indirect contact with infected live or dead poultry. There is no evidence that the disease can be spread to people through properly cooked food.

Controlling the disease in animals is the first step in decreasing risks to humans.

For more Information:

WHO Avian influenza(English)
WHO Avian influenza (Chinese)
WHO Regional Office for Europe overview on avian influenza for public health professionals

Review Articles on Avian Influenza