A 12-year-old unvaccinated girl has become the second child to die after suffering from influenza A since the current flu season began in Hong Kong in late June, the Centre for Health Protection has said.

Centre controller Edwin Tsui Lok-kin said on Wednesday that local influenza activity remained at a high level.

“I urge the public not to take influenza lightly, and to take appropriate preventive measures, including receiving [a vaccination] as early as possible in order to build an immunity barrier in the community and reduce the risk of severe illness and death,” he said.

The girl, who had underlying health conditions, developed a fever, cough and diarrhoea on Saturday, followed by vomiting.

Her condition deteriorated on Monday evening and she was taken to the accident and emergency department of Pamela Youde Nethersole Eastern Hospital in Chai Wan, the centre said. She suffered a cardiac arrest and was resuscitated, then admitted to the paediatric intensive care unit for treatment.

Her respiratory specimen tested positive for influenza A (H1) virus. Her clinical diagnosis was influenza A infection complicated by septic shock, disseminated intravascular coagulation and multi-organ failure. The girl died on Tuesday.

A preliminary investigation found that she had no travel history during the incubation period and had not received the 2026-27 seasonal influenza vaccination. One of her household contacts recently developed mild upper respiratory symptoms, but did not require hospitalisation. The centre will continue to investigate the case, which will be referred to the coroner.

Since the city entered the flu season in late June, 25 cases of severe paediatric influenza infection have been recorded, the same as during the same period last season.

Twenty patients recovered and have been discharged from hospital. One was in a serious condition, two were in a critical condition and two died, including a seven-year-old boy in August.

The boy had previously been in good health and had received the 2025-26 seasonal influenza vaccination. His respiratory specimen tested positive for influenza A (H3) virus. His clinical diagnosis was influenza A infection complicated by shock and encephalopathy.

The rate of severe complications or death following influenza infection was around five times higher among unvaccinated children than among vaccinated children, according to the centre’s data last year.

Among unvaccinated residents aged 65 years or older living in care homes for the elderly, the rate of severe complications was around four times higher than among vaccinated residents.

Since the new academic year began in September, nearly 460 influenza-like illness outbreaks have been recorded in schools, affecting about 2,800 people. Schools and parents have been urged to remain vigilant and take preventive measures. The centre said it expected influenza activity to continue fluctuating at high levels in the coming weeks. Tsui warned that children with influenza could deteriorate rapidly.

Parents should pay close attention to the condition of their children and visit an accident and emergency department immediately if they develop symptoms such as shortness of breath, wheezing, blue lips, chest pain, confusion, a persistent fever or convulsions.