The exact number of staff who haven't received a jab is not known, with the DHB saying not all staff had responded to the survey. It did not provide a figure on how many staff had not responded.
The figures are a slight rise since the last report on the DHB's staff vaccination figures, collected in early September.
Those figures showed that 22.5 per cent of the DHB workforce had not received a single dose of the vaccine, or were unwilling to provide their vaccination status.
Currently, the Whanganui DHB's number of unvaccinated staff is only slightly higher than the worst-performing DHBs, Taranaki and Bay of Plenty, sitting on 80 and 81 per cent of staff with at least one dose respectively.
In a statement, a DHB spokesperson said the organisation had encouraged all staff to be vaccinated.
"DHBs have been strongly encouraging all their staff to get the vaccine and are pleased with Covid-19 vaccination levels across their workforces," the spokesperson said.
"We are confident high levels of our front-facing staff are vaccinated, given that Group 2 were prioritised earlier this year during the Covid-19 vaccination roll-out."
The DHB did not respond to a question on how many of its staff will be required to be vaccinated under the government's new mandatory vaccination policy for clinical health staff.
Last week, Covid-19 Response Minister Chris Hipkins announced that all staff working on the frontline of the country's health system are required to have had one dose by October 30.
Staff who chose not to be vaccinated were at risk of losing their jobs, Hipkins said.
"We are working with the Ministry of Health on understanding the new health workforce mandate and will be working with our staff to ensure maximum vaccination rates," the DHB spokesperson said.
Nationwide, of the roughly 80,000-strong DHB workforce, around 85 per cent are fully vaccinated, with another 5 per cent having received one dose, totalling 90 per cent with some degree of protection.
In Auckland - the centre of the current Delta outbreak - all three DHBs had full vaccination levels between 92 and 94 per cent and first dose levels between 95 and 98 per cent.