Experts have revealed why they're so concerned after two positive COVID-19 cases were just discovered in the Waikato.
One case was found in Raglan and another in Hamilton East - plunging parts of Waikato, including Raglan and Hamilton city, back into alert level 3 for at least five days.
Professor Michael Plank, of Te Pūnaha Matatini and the University of Canterbury, says the fact they're not yet linked to the Auckland outbreak and have been infectious in the community for several days is concerning.
"It suggests there could be additional undetected community cases. Moving this area to level 3 for five days buys some time for testing and contact tracing to establish how widespread transmission in Waikato is," he says in a Science Media Centre statement.
"These events show that, even with a relatively small number of cases in Auckland, keeping the virus contained to one city is difficult. If the Auckland outbreak grows much larger, it will become even harder to prevent COVID spreading to other parts of New Zealand.
"The message is clear: COVID is here and it's a matter of time before it spreads across the country. The very best way to protect yourself against this virus is to get vaccinated as soon as possible."
Lesley Gray, senior lecturer at the University of Otago's department of primary health care and general practice, is concerned that the cases were only picked up because they went to hospital or had a routine surveillance test
"[This] suggests these people were not concerned that they might have acquired COVID-19 in recently weeks," she says.
"We all have to behave as though everyone around us is COVID-19 positive. Mask, hand hygiene, scanning into venues and keep physically distanced. Finally if you are able to, please get vaccinated as soon as possible."
Meanwhile Victoria University of Wellington clinical psychologist Dr Dougal Sutherland warns the jump back to level 3 brings us into "uncharted waters".
"The timing couldn't be worse as it is the first weekend of the school holidays. Therefore, this increase in alert levels will bring disappointment and changes in plans for many, leading to frustration and anxiety for some," he says.
"Up until now New Zealanders have shown a willingness to trust in the science that lies behind the Government's handling of the COVID response. Maintaining this trust will be a crucial component in going forwards and may help temper the frustration those who are affected may experience."