Influenza cases are on the rise and several people have been sent to intensive care wards with a strand linked to the H1N1 virus which caused a pandemic in 2009, a specialist says.
Canterbury District Health Board clinical virologist Lance Jennings said people should protect themselves by getting the seasonal flu vaccine.
The general spread of influenza was expected at this time of the year but what was setting this winter apart was the resurgence of the strand linked to H1N1, Dr Jennings said.
"We've seen patients sadly being admitted to intensive care in the Hawke's Bay and in Dunedin with influenza.
"This influenza has been associated with the ... virus that first came to New Zealand in 2009 and caused the pandemic and has been circulating since then."
The H1N1 strand was no longer a pandemic virus, and its resurgence followed a similar pattern to what happened in north America and Australia last winter.
The worst-hit areas were Canterbury, South Canterbury, Waikato and the Hawke's Bay.