Nurses working at managed isolation facilities across the country have raised concerns about staff shortages and instability.
These problems were formally recognised in an audit by the Ministry of Health in October.
The ministry said the matters have been addressed - but many health care professionals working at border facilities disagree.
The Infection Prevention and Control Audit of Managed Isolation and Quarantine Facilities was released publicly last month. In it, the ministry revealed more facilities have been facing staffing shortages and roster problems.
In a statement to RNZ, the ministry confirmed all matters identified in the audit had been followed up and addressed.
But that is rejected by two of the country's largest nursing unions, which have hundreds of members working in MIQ facilities.
New Zealand Nurses Organisation spokesperson Kate Weston said a number of its members raised concerns in the lead up to Christmas:
"We have been concerned about the sustainability and the staffing. I think it's something we're going to have to put a lot of effort in to, particularly now we've got the more transmissible virus, so we're going to need to ensure that staffing is sustainable, and that those numbers are bolstered."
Weston said she's received reports of staff doing excessive overtime to cover gaps, with some members feeling pressured:
"It is pretty intense work for them and really critically important, so we've been supporting members on an individual basis as they've come forward to us and have been actively working with them to try to improve situations."
These concerns are echoed by the Director of the Nurses Society.
David Wills said the union surveyed 160 of its members working in MIQ facilities last month, and 44 per cent had experienced inadequate staffing.
"Well, it does mean that they obviously at times are having to work overtime. It does mean that they're carrying heavier workloads, missing meal breaks and things like that but, generally, they cope because they have to cope."
But Wills said it's not as simple as hiring more staff.
"Not everyone wants to work in that type of facility, not everyone can work in that facility. There is concern always about the possibility of taking the virus home, some people are having to adjust their activities of daily living because they are working in an MIQ. So all up, staffing has improved over time, but there are still some areas of concern."
Both of the nurses unions say it's time to do a proper stocktake of the country's medical personnel, and find out where the gaps are.
Dr Sally Roberts is a clinical microbiologist at Auckland District Health Board and an advisor to the Covid-19 taskforce.
She said everyone was working hard to keep staff and returnees safe - and while facilities were steadily improving, it was important to remember they were newly established entities.
"Prior to 2020, we didn't have managed isolation quarantine facilities of this nature, and they involve multiple agencies working together who haven't had a working relationship in the past, and the facilities are not designed for managing individuals with infectious diseases, so it's been a big learning curve."
In a statement, a spokesperson for the Managed Isolation and Quarantine service said they were working to improve the continuity of personnel across its facilities.