Wanganui residents are being advised to get a flu vaccine in the next month, with working-age adults potentially most at risk of contracting a nasty bout of aches and pains.
The seasonal flu vaccine programme has been extended to the end of August because a mild start to winter means winter flu rates are still rising.
Ministry of Health figures show more than 17,510 flu vaccines have been distributed in Wanganui District Health Board area this year, and 1.19 million nationwide.
Unichem Wanganui Pharmacy owner Adam Holmes said there had not been "particularly huge numbers" of people getting vaccines.
"There hasn't been that big burst of flu that we've had in the last couple of years.
"It usually takes something like that for people to get going."
A virus expert warns adults aged between 20-49 are particularly at risk of contracting flu this year.
Institute of Environmental Science and Research virologist Sue Huang said the last two weeks had seen an increase in winter flu rates and several strains of H1N1 virus - commonly known as swine flu - were prominent.
In the 2009 global swine flu pandemic, young children in particular were hit hard and have since developed better immunity to the H1N1 virus.
However young adults escaped the worst at the time and did not need to develop such high immunity levels, meaning they were now more susceptible to the virus.
"I would encourage young people to get more vaccinations," Dr Huang said.
Associate Health Minister Jo Goodhew said winter flu cases had not yet peaked.
"As the peak is still to come, hospitals are likely to see more people with the illness, so it is worthwhile to extend the funded vaccination season."
The seasonal influenza immunisation programme is free for people aged 65 years and over, pregnant women, people with long-term health conditions such as severe asthma, and children under 5 who have been hospitalised for a respiratory illness. For anyone else aged six months or older, the vaccine is available for a fee.
Those who are already unwell should seek advice from their doctor, nurse or Healthline (0800 611 116).