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Preliminary Epidemiologic Assessment of Human Infections With Highly Pathogenic Avian Influenza A(H5N6) Virus, China
Hui Jiang1, Peng Wu2, Timothy M Uyeki3
1Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing.
Background:
Since 2014, 17 human cases of infection with the newly emerged highly pathogenic avian influenza A(H5N6) virus have been identified in China to date. The epidemiologic characteristics of laboratory-confirmed A(H5N6) cases were compared to A(H5N1) and A(H7N9) cases in mainland China.
Methods:
Data on laboratory-confirmed H5N6, H5N1, and H7N9 cases identified in mainland China were analyzed to compare epidemiologic characteristics and clinical severity. Severity of confirmed H5N6, H5N1 and H7N9 cases was estimated based on the risk of severe outcomes in hospitalized cases.
Results:
H5N6 cases were older than H5N1 cases with a higher prevalence of underlying medical conditions but younger than H7N9 cases. Epidemiological time-to-event distributions were similar among cases infected with the 3 viruses. In comparison to a fatality risk of 70% (30/43) for hospitalized H5N1 cases and 41% (319/782) for hospitalized H7N9 cases, 12 (75%) out of the 16 hospitalized H5N6 cases were fatal, and 15 (94%) required mechanical ventilation.
Conclusion:
Similar epidemiologic characteristics and high severity were observed in cases of H5N6 and H5N1 virus infection, whereas severity of H7N9 virus infections appeared lower. Continued surveillance of human infections with avian influenza A viruses remains an essential component of pandemic influenza preparedness.
Insights
Highly pathogenic avian influenza A(H5N6) virus infections in humans show similar epidemiology to A(H5N1) but are more severe than A(H7N9). Continued surveillance is crucial for pandemic preparedness.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- Since 2014, 17 human cases of highly pathogenic avian influenza A(H5N6) have been identified in China.
- This study compares the epidemiologic characteristics of A(H5N6) with A(H5N1) and A(H7N9) in mainland China.
Purpose of the Study:
- To compare the epidemiologic characteristics and clinical severity of human infections with avian influenza A(H5N6), A(H5N1), and A(H7N9) viruses.
- To assess the risk of severe outcomes in hospitalized cases.
Main Methods:
- Analysis of data from laboratory-confirmed cases of H5N6, H5N1, and H7N9 in mainland China.
- Comparison of epidemiologic features and clinical severity, including fatality risk and mechanical ventilation rates.
Main Results:
- H5N6 cases were older than H5N1 cases and had more underlying conditions, but were younger than H7N9 cases.
- Hospitalized H5N6 cases had a 75% fatality rate, significantly higher than H5N1 (70%) and H7N9 (41%).
- 94% of hospitalized H5N6 cases required mechanical ventilation, indicating high disease severity.
Conclusions:
- Avian influenza A(H5N6) and A(H5N1) exhibit similar epidemiologic patterns and high clinical severity in humans.
- Avian influenza A(H7N9) appears to be less severe compared to H5N6 and H5N1.
- Ongoing surveillance of human avian influenza infections is vital for pandemic influenza preparedness.