Respiratory health expert David Hui on Saturday urged the public to get vaccinated against flu quickly with the SAR expected to enter the winter flu season soon and at least three influenza indicators logging up more case numbers.

Hui said that according to data held by the Centre for Health Protection, the proportion of respiratory samples, which are compiled from such sources as hospitals, clinics and schools, testing positive for flu rose to 4.6 last week, approaching the baseline peak of 4.94.

The second indicator was a total of 46 influenza outbreaks being recorded in schools and care facilities, up from 14 the week before.

The third saw admissions for flu at Hospital Authority facilities hitting 0.3 per 10,000 patients, up from the typical number of 0.27, Hui said.

The Chinese University professor said predicting how long the upcoming flu season would last was difficult as that depended on which flu strain was dominant in the community.

"For example, in August 2023, the dominant strain was H3N2, and after that it was followed soon after by H1N1 in 2024, so the flu season lasted for a long period," Hui said.

"This time around, the flu season started in September and ended in January, but now there are more infections again. For now, H3N2 is still the most prevalent, so if it remains the prevalent strain, the flu season might not be too long as a lot of people had gotten infected and recovered earlier," he said on a radio programme.

"But if another strain becomes prevalent like in 2023 and 2024, then the winter flu season may last longer," he added.

Hui said that with more foot traffic and family gatherings as the Lunar New Year draws closer, people should observe strict personal hygiene and wear masks in busy areas, as well as get vaccinated as soon as possible to protect themselves.

He cited present vaccination rates – of only around 20 percent for those aged between 50 and 64 and between six months and two years old as well as about 46 percent for the elderly – for the urgency in getting people to get jabs.

Hui pointed out that herd immunity is established only when 70 percent of the population gets the flu jab, saying vaccines could help reduce complications among patients and admissions at hospitals.