The health system is preparing for a potentially difficult winter flu season, as the H3N2 Subclade K (Super-k) influenza virus heads for New Zealand’s shores.

The variant spread across the United States and Europe last year and has already arrived in Australia. It is spreading faster than typical seasonal influenza, according to Australia’s national science agency CSIRO.

A professor at Otago University and head of the department of Paediatrics and Child Health, Peter McIntyre, told RNZ’s Nine to Noon that Super-k did not seem to be any more severe than historic flu strains, but it was less well-matched to the vaccine.

The virus had actually already arrived in the country towards the tail-end of the 2025 flu season, McIntyre said.

Fortunately, those who were considering how to formulate this year’s flu vaccine had included a similar strain, which would make it much more effective than the protections the Northern Hemisphere had, he added.

The cycle of respiratory viruses like the flu was becoming less predictable post-Covid.

“The way that flu strains work during the year has changed a bit from the predictable winter peak with not much going on in the rest of the year, to a lot more unpredictability.”

Although the vaccine provided limited protection against super-k, those most at risk should get vaccinated as early as possible, he said.

“For those at higher risk of complications from the flu, which is anyone over the age of 65, and particularly those over the age of 75 or 80 ... it’s a very good idea to get in right now with your flu vaccine, because the season may be with us sooner than we think.”

Another option, the Fluad vaccine, was more effective, but it was currently not funded in New Zealand, McIntyre said.

“There are good arguments in favour of it, and the immunisation advisory centre has been lobbying for this for a while.

“Particularly for our most frail elderly – so people in residential aged care who are most at risk of severe flu, I think there’s a very good case for funding it, but at this stage it hasn’t got high enough on the Pharmac wish-list.”

- RNZ