The Centre for Health Protection of Hong Kong’s Department of Health on Saturday urged residents to get vaccinated against flu after three more children got infected and developed severe complications.

CHP Controller Edwin Tsui Lok-kin said influenza activity had increased last week and remains at a high level, with a total of 16 cases of severe pediatric influenza recorded late June.

He urged the members of the public to get their jabs as soon as possible after the seasonal influenza vaccination programs start on Sept 17.

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“The overall number of severe influenza cases among children is comparable to that of previous flu seasons,” Tsui said. “However, owing to widespread influenza transmission in the community in recent months and the substantial rise in infections, the number of severe cases has increased accordingly.”

The first case involves a six-year-old girl who’s in a critical condition after developing a fever, runny nose and cough on Sept 3, and was admitted to the Accident and Emergency Department at Ruttonjee Hospital in Hong Kong Island’s Wan Chai District.

The girl later had convulsions and was transferred to the pediatric intensive care unit at Pamela Youde Nethersole Eastern Hospital where doctors determined she had influenza A complicated with encephalopathy.

The second patient is a three-year-old girl who’s in serious condition after developing a fever on Sept 2, and was taken to a private hospital.

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The following day, she had convulsions and was sent to the Accident and Emergency Department of Queen Elizabeth Hospital where she was admitted to its specialized unit. She was diagnosed with influenza A complicated with septic shock.

The third case involves a 15-year-old boy, who remains in a serious condition at Queen Mary Hospital.

He first developed a fever, runny nose and malaise on Sept 3, and was taken to a private clinic. Due to persistent symptoms, he was admitted to a private hospital the following day and subsequently transferred to the intensive care unit due to low blood pressure. Doctors said the patient had influenza B, complicated by septic shock.

The CHP said its preliminary investigation showed that none of the three children had any travel history during their incubation periods, and their household contacts remained asymptomatic.

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Two classmates of the six-year-old girl developed mild influenza symptoms recently, but were not hospitalized. The center advised the school to take appropriate infection control measures.

“We expect influenza activity to remain at a high level during the initial period of the new school year, with possible influenza outbreaks in schools. Therefore, schools and parents must remain vigilant and take preventive measures,” Tsui said.