The Centre for Health Protection (CHP) of the Department of Health (DH) of Hong Kong S.A.R is (February 21) investigating a case of influenza A (H9) infection affecting a 22-month-old girl.

The patient has developed fever and cough with sputum since February 15 and was brought to Union Hospital for medical advice on February 16. No hospitalisation was required at that time. Her clinical specimen was tested positive for the influenza A (H9) virus today upon testing by the Public Health Laboratory Services Branch of the CHP. Subtyping result is pending. Her clinical diagnosis was avian influenza. She is in stable condition and arrangements have been made for her to be admitted to isolation ward of Princess Margaret Hospital for further treatment.

Preliminary investigation of the CHP revealed that the patient had visited Zhongshan during the incubation period. The patient had no direct poultry contact recently, nor consumption of undercooked poultry, or contact with patients. One of her home contacts developed sore throat on February 17 who had taken medication and the symptom had subsided. Her other home contacts are asymptomatic so far. Investigations are ongoing.

The CHP will inform the health authority of Guangdong and the World Health Organization of the case.

Novel influenza A infection, including influenza A (H9), is a notifiable infectious disease in Hong Kong. Influenza A (H9N2) infection is a mild form of avian influenza. Nine cases of influenza A (H9N2) had been reported since 1999. The recent case was an imported case reported in 2020. No deaths have been recorded so far.