More than 85 per cent of Hong Kong infants and toddlers remain unvaccinated against flu, a leading respiratory disease expert has said, while warning of the approaching winter peak after more than 20 severe influenza cases were recorded among children, including two deaths.

David Hui Shu-cheong, a professor of respiratory medicine at the Chinese University of Hong Kong, said on Sunday the summer flu peak was slowly receding and expected to bottom out by the end of November or the beginning of next month.

But the winter flu season, which usually occurs between January and March each year, could bring about another peak shortly, he said.

Hui noted that this year, 1.33 million people had been vaccinated against influenza, which was 3.9 per cent higher than the same period last year.

“Only 14 per cent of high-risk children aged six months to two years have been vaccinated so far,” he told a radio show, adding that the low vaccination rate was insufficient to build up herd immunity.

He added that around 80 per cent of the population remained unvaccinated against influenza.