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Annual flu epidemics lead to severe illness, life-threatening complications, and death, especially in high-risk groups such as young children, the elderly, pregnant women, the obese, people with underlying health problems, and Indigenous populations.

Meanwhile, the potential for a severe pandemic is a constant threat, for example, the 2013 A/H7N9 influenza A “bird flu” virus that emerged in China in 2013.

This is a severe flu affecting people in close contact with infected birds and has a 40 percent mortality rate. From October 2016 its “fifth wave” has been responsible for 713 known human cases, including 205 deaths, and A/H7N9 mutations are raising concerns around the strain’s potential to develop pandemic-facilitating human-to-human transmission.

In a new study, a group led by researchers* at Melbourne’s Doherty Institute, a joint venture of the University of Melbourne and Royal Melbourne Hospital together with Shanghai Public Health Clinical Centre, Fudan University, identified key differences in immune responses between A/H7N9-infected patients who recover and those that died. 

Published today in Nature Communications the study found, in people hospitalised with A/H7N9, survival was strongly correlated with a specific activated immune cell being temporarily present in the patient while prolonged persistence of this type of immune cell was consistently observed in samples from patients that died.

The study was co-led by University of Melbourne Professor Katherine Kedzierska, who explains:

“Importantly, we’ve found that by monitoring some special activated white blood cells may be able to predict life or death outcomes for severe flu infections. The study provides a novel and fundamental contribution to our understanding of mechanisms underlying dysfunctional immunity in flu, and it may be generalisable to other severe viral infections.”

Study co-author, Dr Zhongfang Wang, a Research Fellow in the Kedzierska laboratory, adds: 

“Overall, this work points to the possibility of limiting severe disease from pandemic flu.” 

The next step for the researchers is to identify precisely how the ebb and flow of these specific immune cells mediate recovery in some individuals and not others.

*This research was a collaboration between the University of Melbourne, Shanghai Public Health Clinical Centre at Fudan University, St. Jude Children’s Research Hospital, The Kirby Institute UNSW, Alfred Hospital and Monash University. The study was jointly led by Professor Katherine Kedzierska from the Department of Microbiology and Immunology at the Doherty Institute, and Professor Jianqing Xu from Shanghai Public Health Clinical Centre, Fudan University. Dr Zhongfang Wang, a Research Fellow in the Kedzierska laboratory, worked with Fudan University-based experts on the research.