Hong Kong's Centre for Health Protection (CHP) said on August 11 that it was investigating a severe paediatric influenza A infection in an 18-month-old boy with good past health. He developed fever, a runny nose and cough on August 8 and was taken to a private clinic the next day; after a convulsion at home he was brought to Queen Elizabeth Hospital's emergency department, found drowsy with low blood pressure and admitted to the paediatric intensive care unit. His respiratory specimen tested positive for influenza A, and his diagnosis was influenza A infection complicated with encephalopathy and septic shock. He remained hospitalised in serious condition.

The CHP's preliminary investigation found the boy had not received seasonal influenza vaccination in the previous season (2025/26) and had no travel history during the incubation period. One household contact had recently developed a mild fever and upper respiratory symptoms, required no hospitalisation and had recovered.

Since Hong Kong entered the influenza season in late June, a cumulative total of eight severe paediatric influenza cases had been recorded, including this one, of which one died, the CHP Controller, Dr Edwin Tsui, said. He said influenza activity was expected to remain high in the coming weeks. Last week, 9.94 per cent of respiratory specimens tested positive for seasonal influenza viruses and the public hospital influenza admission rate was 0.73 cases per 10 000 population. Influenza A (H3) and A (H1) each accounted for 45 per cent of detections, with influenza B at 10 per cent. Dr Tsui said the A (H3) virus belongs to the K subclade circulating globally since last August, with no evidence it causes more severe illness.