As Australians face a "horror" flu season, and "a fair bit" already here, New Zealanders cannot afford to be complacent, experts say.
Less than a month into the official flu season, early signs show we cannot assume it will be another mild year, Immunisation Advisory Centre director Dr Nikki Turner said.
The number of flu-like illnesses reported in the first half of the month remained on par with other years but a higher-than-usual proportion of those cases were being confirmed as influenza rather than other respiratory illnesses, Institute of Environmental Science and Research data showed.
Nearly 35 per cent of samples tested by GPs and hospital staff came back positive for influenza in the week ending May 12 - one of the highest rates for the same time period in recent years.
"There are early signs that there is a fair bit of flu around," Turner said.
But the prevailing strains so far were covered by the vaccine, she said.
In Australia, 68 people had already died in a "horror" flu season, the Guardian reported.
Peak flu season was usually between July and October but deaths were already at record levels in many states - and the worst was yet to come, health officials warned.
Turner said New Zealand's flu season did not always mirror Australia's but their situation meant the medical community would remain vigilant.
"There's only a small amount of water between us and Australia and a lot of travel," she said.
Turner encouraged New Zealanders to get the flu vaccine to lessen the chance they and those around them would be struck down by the illness.
At best it could leave you laid up in bed feeling miserable, while at worst it led to hospitalisation and was on occasion fatal.
Those worst affected were usually children, the elderly and those with other pre-existing conditions.
Turner said it was important people got the flu jab soon because it took up to two weeks for the vaccine to take effect.
Institute of Environmental Science and Research public health physician Dr Sarah Jefferies confirmed influenza viruses were circulating in the New Zealand community earlier this year but the numbers remained low.
She said there were four seasonal influenza viruses circulating globally: A(H1N1), A(H3N2), B/Yamagata lineage and B/Victoria lineage.
We cannot predict from Australia's experience what the New Zealand season will be like.
"Testing from earlier in the year indicates that strains circulating in New Zealand should be well covered by the 2019 seasonal influenza vaccine," Jefferies said.
She said it appeared the two main strains in Australia were the A variants and information available so far suggested they were a good match to the 2019 vaccine strains.
"We cannot predict from Australia's experience what the New Zealand season will be like. 2017 is a good example, where Australia had relatively high influenza activity in many parts of the country and New Zealand had a low season overall," she said.
Otago University senior lecturer in virology Dr Matloob Husain said there was some concern Australia's situation could "spill over" to New Zealand because of the close ties and frequent travel between the two countries.
He stressed the need for people to be vaccinated each year because the virus was constantly evolving and each year's vaccine differed slightly in an effort to predict and combat the most recent variant.
As of Tuesday, 1,173,649 doses of the influenza vaccine had been distributed to medical practices around the country, according to the Ministry of Health.