Flu season passes peak - but watch out for a second wave

Many doctors are breathing a sigh of relief as the flu season passes its peak - but there is a warning of a sting in its tail.

Hospitalisations from flu-like illnesses have dropped sharply in the latest figures - to about 10 in 100,000.

Children under-five have fallen for the first time since 2 August.

College of General Practitioners clinical lead Luke Bradford said GPs had also noticed a big drop-off in the community.

After a mountain of cases this year, there was now a level of herd immunity from both vaccinations and people who had the virus, he said.

"That's why the peak drops off each year - it gets to the point where the virus can't pass on to the next person at the same rate, because they are immune to it."

Auckland GP and Immunisation Advisory Centre senior Māori medical advisor Mamaeroa David said it was great to see the drop, as warmer weather hit, but another spike may yet come.

A resurgence or a long tail of winter illnesses was not unusual, she said.

"Often every year, we relax, but I feel like we've got another cold spell to come and that's when we get another round of sickness come through," she said

Influenza A had driven the big surge in winter illnesses this year, with the super infectious K strain, and influenza B could still take off.

Even though hospitalisations had dropped in the latest figures, they were still very similar to the peak of last year's outbreak, another illustration of how big this season was.

Both doctors said anyone who had not been vaccinated for flu should still take the chance to get one.

The vaccine was now free for under-fives, for 65 and over, and for many others vulnerable to serious infections.

Bradford hoped people would remember how bad this season had been when it came time for vaccinations next year.

-RNZ