An unvaccinated four-year-old girl infected with influenza A died on Monday. In the past two weeks, two other girls, aged eight and six, also died after contracting the flu, while a three-year-old girl with the virus is fighting for her life in Queen Elizabeth Hospital.

Low herd immunity in Hong Kong may prolong flu season, experts warn

Eighteen other children have developed severe flu conditions in the current season, and most did not receive the latest flu vaccine.

The three fatalities compare with one or two children dying from flu in the peak periods from 2017-18 to last year.

Wong stressed vaccination could reduce the risk of hospitalisation by 40 to 60 per cent. But according to the latest figures, about 20 per cent of residents of homes for the elderly and nearly half of children and those aged 65 or above had not yet been vaccinated.

Dr Chuang Shuk-kwan, head of the centre’s communicable disease branch, warned that the city’s flu season, which started in early January and was entering its 16th week, could last even longer due to changes in the dominating flu strain.

“The strain of the virus has shifted from influenza A subtype H3 to subtype H1,” she said. “We may have another round of infection that is expected to take a few weeks. But it is difficult to predict how long the flu season will last.”

She could not rule out further changes given influenza B viruses dominated in certain overseas locations and residents were travelling frequently.

But there was no need to adopt special measures over the “golden week” holiday that would begin on Wednesday, Chuang said.

Authorities were already conducting temperature checks at crossing points and transferring travellers to hospital if necessary, she noted.

Hong Kong’s flu season usually lasts eight to 12 weeks, but Chuang said the timing during the first one or two years after the Covid-19 pandemic ended had been unstable. For example, the summer flu season, which usually took place in July and August, spanned August to October last year.

Health officials said flu and Covid-19 cases remained at a high level.

Unvaccinated 8-year-old Hongkonger dies after contracting flu

Dr Larry Lee Lap-yip, a chief manager at the Hospital Authority, also noted that there had been growing pressure on paediatric wards, with occupancy rates hovering around 110 per cent in recent days.

Visits to accident and emergency departments, as well as occupancy rates in medical wards, were also at a high level.

The authority would increase the number of beds in paediatric wards if needed, and older children would be transferred to free up space for younger ones, Lee said.

The four-year-old girl who died on Monday developed a fever and sore throat last Thursday.

She was admitted to a private hospital the next day and was later sent to Pamela Youde Nethersole Eastern Hospital in a critical condition on Saturday, but her condition continued to deteriorate.

Chuang said overseas academic literature indicated that while personal health conditions and heredity factors might make a person more prone to serious infection, vaccination could still offer certain protection.

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Dr Mike Kwan Yat-wah, an honorary associate professor at the University of Hong Kong’s department of paediatrics and adolescent medicine, warned that the flu season could become year-long if shifts in dominating strains continued to prolong it.

While Hong Kong ordered schools to close to curb flu outbreaks in 2018 and 2019, Kwan said he did not agree with such moves now

“We would need to have a normal life … we would need to use scientific ways to prevent infections,” he said.

He urged children to get inoculated and for the wider adoption of nasal spray vaccine.