Kaupapa Māori vaccinators and testers going "hell for leather" are having to be forced to take days off, while Pasifika contact tracers are "frayed at the edges", according to bosses.
Burnout has become a primary concern.
Overall there are have been 38,000 contacts identified this outbreak, compared to fewer than 2000 in the last February outbreak.
Pasifika Medical Association senior member Dr Colin Tukuitonga said those numbers were "enormous" and bilingual contact tracers were thinly spread - particularly those who spoke Sāmoan - despite additional interpreters being brought in.
"We have a very limited number of people with the right skills and expertise and so the pressure is on those few people. And contact tracing is a seven day a week, 24/7 activity so you can imagine from that the strain that they're under."
He said many were "frazzled" and "frayed around the edges".
Te Whānau O Waipareira Trust kaimahi are also at high risk of burnout, vaccinating up to 3000 people a day and taking up to 800 swabs.
Trust chief executive John Tamihere (Ngāti Porou ki Hauraki, Whakatōhea) said they started at about 7.30am and worked into the early evening, daily.
"We need to go hell for leather in lockdown [level] 4 ... because when people go back to work the number of no-shows on appointments increases dramatically."
Tamihere said staff had to take 48-hour breaks or they would "work until they drop".
"A number of them you have to force to stand down. They're in a mode. It's like they ain't gonna stop fighting until they run out of ammunition."
Pasifika and Māori organisations running vaccinating and testing stations are often also operating GP services, kai support and social services.
Tāmaki Makaurau GP and Hauora Coalition clinical director Dr Rawiri Jansen (Ngāti Raukawa) said that was "an incredible amount of work" that often left staff "quite stressed and quite stretched" in lockdown.
But he felt burnout was preventable, with strict rostering and compulsory time off, to ensure people recharge with loved ones.
That's what has helped him get through.
"I want to honour their support for me, by taking time off, by avoiding burnout and spending some quality time with them because, at the end of it, it is about whānau."
Dr Jansen said it was important that service managers modelled self-care by taking days off too.