Health authorities in Hong Kong urged parents on Sunday to have their children vaccinated against influenza after a 14-year-old boy developed a severe infection complicated by pneumonia and septic shock.

​The Centre for Health Protection of the Department of Health reminded parents that free seasonal influenza vaccination (SIV) remains one of the most effective methods to prevent the flu and reduce the risk of serious complications or death from infection.

“I once again urge all individuals aged 6 months or older, except those with known contraindications, to act promptly if they have not yet received an SIV,” said Edwin Tsui Lok-kin, CHP controller.

“This includes those who contracted influenza during the summer influenza season in order to guard against other circulating virus strains that may emerge during the upcoming winter influenza season.”

Tsui noted that the SIV coverage rate for children aged 6 months to under 2 years in the city is only about 23 percent.

“Although this represents an approximate 4 percentage point increase compared to the same period last year, it is still much lower than that of other age groups,” he said.  

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The CHP said the 14-year-old boy, who has an underlying illness, developed a fever, shortness of breath and cough since Friday. He sought medical attention at the Accident and Emergency Department of Pamela Youde Nethersole Eastern Hospital on Saturday and was transferred to the paediatric intensive care unit on the same day.

The patient is currently in critical condition and the clinical diagnosis is influenza A infection complicated with severe pneumonia and septic shock.

A preliminary investigation revealed that the boy received the 2025/26 SIV only three days before onset of illness. Since it takes two weeks for the body to develop sufficient protection after vaccination, he was not protected by the vaccine.

The boy had no travel history during the incubation period while two of his household contacts, one of whom also tested positive for the influenza A virus, developed mild respiratory symptoms.

The CHP said the summer influenza season that just ended had recorded 25 severe paediatric influenza cases, including three that were fatal.

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The affected children were aged between 6 months to 17 years old. Among them, 20 cases (80 percent) had not received an SIV (including one case who received the 2025/26 SIV only four days before onset of illness).

“Influenza activity may rise again as the weather remains cold in the first quarter of this year and it cannot be ruled out that the circulating virus strains may change as the winter influenza season approaches,” Tsui said.

"Although the influenza activity has declined to below the baseline level at the moment, outbreaks caused by influenza viruses still occurred in schools and residential care homes.”