About 15 per cent of nurses at Canterbury District Health Board (DHB) are off because of Covid-19.
And 18 per cent of health workers at a Porirua hospital are absent as the impact of the outbreak continues to grow outside Auckland.
Nurses were the hardest hit health workers at Canterbury DHB but allied health workers - including medical technicians, physiotherapists and lab workers - were not far behind with 13 per cent of them off.
And 9 per cent of doctors were affected.
Canterbury DHB incident controller Helen Skinner said, in total, about 510 staff were off either with Covid-19 or as a household contact.
Staff left behind were going "above and beyond" to help keep essential services running, she said.
Part-time workers were working extra shifts, fulltime staff were doing overtime, and people were being redeployed to areas where there were shortages, she said.
About 15 per cent of people turning up to the emergency department had Covid-19.
Wellington's hospitals were also dealing with significant numbers of clinical staff off because of Covid-19.
Nearly 500 health workers were off at Wellington Regional Hospital, about 14 per cent of a staff 3500.
And 18 per cent of the 340 health staff at Kenepuru Community Hospital in Porirua were off, with 6 per cent off at Hutt Hospital (out of 1640 staff).
At Lakes DHB, which included Rotorua and Taupō Hospitals, 8 per cent of the clinical workforce was off because of Covid-19.
Nursing staff there had been bolstered by the return of about 20 nurses from Rotorua's managed isolation hotel, a spokesperson said.
At Taranaki DHB, 4 per cent of staff were off because of the virus, there were 2.5 per cent off at Northland and just under 5 per cent at Hawke's Bay.
In Waikato, 214 out of about 8000 staff were off, most of them clinical.
It was seeing a drop in the number of patients coming through its emergency department with Covid-19 - just 3.3 per cent on Tuesday, down from 7.3 per cent a week prior.
Southern DHB was less impacted, with 92 staff out of 5000 off because of Covid-19, but community cases were still rising in the region.
There were just 46 people off in Whanganui.