The Nurses Organisation says it is troubling an Auckland quarantine worker has tested positive for Covid-19.
This is the third managed isolation worker who has caught the virus in the past week.
Two workers at a managed isolation facility in Christchurch also tested positive for Covid-19.
New Zealand Nurses Organisation spokesperson Kate Weston said Counties Manukau District Health Board was failing to address "serious systemic problems" at Auckland isolation facilities.
"Members tell us there is not consistent access to N95 masks, and that they are not being fit tested for these masks, which is important for their safe use," Weston said.
"While the DHB say they have been fit testing for the last couple of weeks, the DHB could not tell us how many staff had been fit tested or when procedures would be in place to fit test all staff."
Members said there were also no clear plans to address short-staffing.
"Inadequate access to PPE and poor training in its use has been an issue we've known about since this all began, and here we are again. That this is still happening is completely shocking and a matter of huge public concern," Weston said.
"New Zealand is in a privileged position internationally, but workers protecting our borders are becoming infected because an overwhelmed system cannot cope.
"More must be done to protect our workers and protect our community."
Weston reiterated calls for an urgent review of how quarantine facilities are run.
"Until these issues are resolved, the risk to New Zealanders will remain very real, because we can expect more nurses and other health workers will contract Covid-19," she said.
RNZ has contacted Counties Manukau District Health Board, but has not yet had a response.