Avian influenza A(H5) viruses A(H5N1), Viet Nam Since the last risk assessment of 26 February 2024, one human case of infection with an A(H5N1) influenza virus was notified to WHO from Viet Nam on 25 March. A 21-year-old male from Khanh Hoa province developed fever and cough on 11 March 2024. On 15 March, he was admitted to a local hospital due to persistent symptoms, including abdominal pain and diarrhea. On 17 March, he was transferred to a provincial hospital as his condition worsened and between 18-19 March, he was treated in the intensive care unit for pneumonia. On 19 March, samples were collected for real time polymerase chain reaction testing by the Pasteur Institute of Nha Trang (PI NT) and were positive for influenza A(H5) virus. On 20 March, the patient was transferred to another provincial hospital with a diagnosis of severe pneumonia, severe sepsis and acute respiratory distress syndrome. Unfortunately, the patient passed away on 23 March.

On 22 March, result of genomic sequencing conducted by PI NT identified the virus from the patient as an avian influenza A(H5N1) virus. Genomic sequencing is also being conducted by the National Institute of Hygiene and Epidemiology (NIHE). Initial results from the case investigation revealed that during the second and third weeks of February 2024, the patient had been trapping wild birds. Since then, he had no reported contact with dead or sick poultry nor with anyone with similar symptoms. At the time of reporting, no further cases were suspected among close contacts. Since 2003, 129 human infections with influenza A(H5N1), including 65 deaths, have been reported in Viet Nam. The most recent avian influenza A (H5N1) case was reported in October 2022 from northern province of Phu Tho, Viet Nam. According to reports received by the World Organization for Animal Health (WOAH), various influenza A(H5) subtypes continue to be detected in wild and domestic birds in Africa, Asia, Europe and the Americas. Infections in non-human mammals are also reported.

A(H9N2), China Since the last risk assessment of 26 February 2024, three human cases of infection with A(H9N2) influenza viruses were notified to WHO from China (see Table 1). The two cases with mild illnesses were detected through routine influenza-like illness. All cases have recovered. Environmental samples collected around the market and backyard of the first and second cases tested positive for influenza A(H9) viruses, while environment samples associated with the third case tested negative for influenza viruses. No further cases were suspected among contacts of these cases. 3 Table 1. Human cases of influenza A(H9N2) reported to WHO from China from to 27 February to 4 March 2024. Onset date Reporting province Age (years) Gender Severity Hospitalization date Poultry exposure 2 Feb 2024 Guangxi 3 Male Severe 5 Feb 2024 Poultry from live poultry market 11 Feb 2024 Jiangxi 11 Male Mild 15 Feb 2024 Backyard poultry 17 Feb 2024 Guangdong 3 Male Mild 19 Feb 2024 Backyard poultry Avian influenza A(H9N2) viruses are enzootic in poultry in Asia and increasingly reported in poultry in Africa.