A paediatrician on Saturday has urged the public not to lower their guard this flu season, urging Hongkongers to get vaccinated for what could be a severe winter flu season.

Mike Kwan, from the University of Hong Kong's Department of Paediatrics and Adolescent Medicine, said infection numbers are expected to spike in January.

Kwan said the SAR's flu season might be comparable to Australia's experience earlier this year.

"Just looking back [at] Australia, the Southern Hemisphere, the flu season in fact was quite severe. So I expect, in the Northern Hemisphere this winter, our flu season will still be quite severe," Kwan said after appearing on a radio programme.

"This is why we are advocating the flu vaccination to all our citizens. The severity of flu infections in our community really depends on the percentage of our vaccinations, what we regard as herd immunity."

Kwan said the vaccination rate among children aged six months to three years was relatively low.