Australia is experiencing a quieter flu season than usual but experts will today issue a warning that cases are on the rise.

Influenza Specialist Group chairman Alan Hampson said yesterday that influenza, including the predominant strain swine flu, was already a problem in Asia.

He urged people planning to travel to Asia, including for the New Delhi Commonwealth Games, to be vaccinated against influenza.

''Based on surveillance data, the timing for the Commonwealth Games in Delhi is around the usual peak time for influenza in that region,'' Dr Hampson said.

''This has obvious implications for the athletes, but also for other team members and spectators. It has been found that highly trained athletes tend to be more susceptible to respiratory infections such as influenza.''

Dr Hampson said influenza cases were increasing in some districts of New Zealand, which usually shortly preceded infections in Australia.

At least 454 people with swine flu have been hospitalised in New Zealand this year.

Australian National University infectious diseases expert and Influenza Specialist Group member Sanjaya Naresh Senanayake said Australia might be approaching the peak of flu season.

He urged people, particularly those in high-risk groups, to consider being vaccinated.

For more on this story, including advice for those with flu symptoms, see the print edition of today's Canberra Times.