Version: April 2024
H7N9 is a bird flu strain of the species Influenza virus A. First reported in China in 2013, it primarily affects poultry. Transmission to humans has been associated with direct exposure to infected poultry or contaminated environments. Most infected individuals experience severe respiratory illness, including pneumonia and acute respiratory distress syndrome. Despite its high mortality rate among humans, H7N9 virus does not easily transmit from person to person, limiting its potential to cause a pandemic. Effective control strategies in poultry are key to reducing human risk.
In the mainland of China from 2014 to 2024, the H7N9 virus recorded the most significant infection rate between January 2017 and June 2017, reaching a peak in January 2017 with 192 cases. The years 2014 and 2015 displayed a significant number of cases but less compared to 2016 and mostly 2017. After a severe outbreak in 2017, the infections sharply declined with only sporadic cases in 2018 and a single case recorded in 2019. Thereafter, no new cases were reported from 2020 onwards.
Concerning deaths, the highest number resulted from January to April 2017, with 79 deaths in January alone, reflecting high case virulence and fatality during this period. The mortality count fluctuated but remained relatively high from 2014 to mid of 2017, after which it significantly diminished. Despite reducing case reports after 2017, death occurrences persisted up to March 2018. No deaths were recorded from April 2018 henceforth, corresponding with the downturn in infections over that period.