Health authorities said the outbreak had peaked in Auckland but was still growing nearly everywhere else.
Pinnacle Midlands Health Network has 85 practices across the middle of the North Island and medical director Jo Scott-Jones said some were seeing huge numbers of patients with the virus.
There were surges in Taranaki, Tairāwhiti, Lakes and Waikato DHB areas, he said.
"What we're seeing is being described as a Mexican wave, sort of travelling down the country," he said.
