An already stressed health system could become overwhelmed when border restrictions are lifted, the midwives union is warning.
"It's worrying that a number of sports bodies, businesses and particularly tourism operators, are calling for all forms of self-isolation to be scrapped. The attitude seems to be 'just let anyone into the country and no worries if we all get Omicron'. Anyone who thinks that will work out well for us is deluded," Midwifery Employee Representation & Advisory Service (MERAS) co-leader Jill Ovens said.
The problem would not be a lack of hospital beds but a shortage of staff if large numbers of health workers are off sick with Omicron, Ovens said.
DHBs and the Ministry of Health are already working with health sector unions on preparedness plans, in anticipation of 20 percent or more staff off sick at any one time, she said.
Already, there are severe shortages in many health professions - midwives, nurses, and allied health. There are maternity units that should have four midwives on duty but struggle to get two.
"I don't think those calling to scrap self-isolation understand we don't have the staff to run our hospitals, aged care facilities and community services even without Omicron circulating. Imagine what will happen if we all get Omicron at once."
This winter could be especially difficult if there was a surge of influenza and other respiratory illnesses, Ovens said.
"The medical experts are telling us, these are likely to be much more severe," said Ovens.
The World Health Organisation (WHO) believes the number of Covid-19 infections has peaked, but Ovens said the Northern Hemisphere is going into summer when infections typically decline and Aotearoa will soon head into winter.
The stress on those who are at work will be huge and will lead to even more staff taking sick leave, if not leaving the health sector altogether, she said.
"We hope people understand this but we don't think they do."
Ministry of Health plans to move staff between district health boards to address worker shortages were flawed because many DHBs were already short of midwives, she said.