The country's 20 district health boards (DHBs) warned the Government a year ago of "critical workforce issues", calling it an "unsustainable situation" with some overloaded hospitals at "code red".
Since then, health worker shortages have only exacerbated, with unions saying the country is 4000 nurses short as the health system groans amid the "twindemic" of Covid-19 and the flu as winter bites.
On July 28 last year, Hawkes Bay DHB chief executive Keriana Brooking, representing the 20 DHBs, wrote they were "experiencing significant challenges to maintain safe levels of services that are being exacerbated by workforce supply challenges".
"Most importantly this includes the risk that existing overseas trained employees will leave due to an inability to secure their futures as residents of New Zealand," said the letter, addressed to Carolyn Tremain chief executive of the Ministry of Business Innovation and Employment, and responsible for immigration.
In her July 2021 letter, Brooking said hospitals were also experiencing" very high levels of occupancy at present and some sites are even in 'code red' where they are deemed to be at extreme levels".
"This is obviously an unsustainable situation and places even more pressure on our existing workforce.
"We are very concerned about this situation and for the potential for further deterioration if there are no changes to assist with at least securing the existing workforce."
Increasing hospital demand was flowing into ICU, exacerbated by RSV and other winter illnesses and impacting ability to "surge" capacity, she said.
"This will have long-term impacts on the health and wellbeing of New Zealanders."
DHB heads asked for current overseas-trained staff to be given a "direct and prompt path to residency" and overseas health professionals facilitated to enter New Zealand as required to "avert a crisis in the health sector".
This letter was written ahead of some major changes in immigration settings, including the one-off residency process estimated to assist about 170,000 people.
In May the Government also announced a fast-track residency process through which some healthcare workers could immediately gain residency, but nurses were left off, having to wait two years.
National Party health spokesman Dr Shane Reti said the letter's "gloomy prognosis from the sector has come true".
He accused Health Minister Andrew Little of spending too much time on health reforms, coming into force on Friday, than ensuring access to healthcare.
"New Zealanders are now missing out on health care because Little has failed to act on warnings from the sector.
"Meanwhile, New Zealand is missing out on nurses to Australia because the Government has refused to put them on the fast-tracked residency pathway.
"Now we are dangerously 4000 nurses short and have a health sector slowly falling apart at the seams.
"Andrew Little needs to explain why he didn't listen to pleas from the sector last year about the coming workforce shortage, and why he didn't take urgent action to bring more workers in from overseas."
Reti questioned the Government about the letter in the House.
Education Minister Chris Hipkins, speaking on behalf of Little said that feedback was taken seriously.
"It's one of the reasons that we still have Covid-19 protection measures in place.
"I would note that our health system would likely be under significantly more pressure if all of our remaining Covid-19 protections were removed, which some in this House—who sit over on the other side—have been arguing for."
Hipkins said the Government had been aware for "some time" significant pressure was coming due to Covid-19 and a more challenging flu season with the border reopening and bringing in new bugs.
There was also a global shortage of trained healthcare workers, he said.
"That is something that New Zealand is experiencing—the same as many other countries are."
Hipkins said the Government had been working through the border restrictions period to ensure health workers could come into the country to fill the vacancies.
The two-year requirement for nurses under the new fast-track residency criteria was "because we don't want them coming into the country and then not working as nurses", Hipkins said.
Brooking has been approached for comment.