The flu epidemic has taken hold, with three times as many hospital admissions across the country due to the winter malady than last year.
According to Auckland Hospital, winter illnesses are at a high and the hospital is experiencing its "busiest period in history".
It is asking patients to visit their GPs where possible.
In July, the hospital had 136 influenza hospital admissions, up from 41 in July last year, Fairfax has reported.
There have been 96 people admitted with flu-like symptoms in Wellington Hospital in July as well.
Institute of Environmental Science and Research public health physician Jill Sherwood says rates of influenza were three times higher than last July.
This year it was seeing 50 cases per 100,000 people, compared to 17 at the same time in 2016.
Ms Sherwood said last year's mild winter meant rates were always likely to be higher this July.