Prime Minister Jacinda Ardern will be in Whanganui on Wednesday to support the vaccination drive in the area.
The Whanganui, Rangitīkei and Ruapehu areas are now expected to hit 90 per cent full vaccination by mid-December, according to the Whanganui DHB.
The DHB's acting chief executive Graham Dyer said that was based on current projections.
In an interview with the Chronicle on Friday, Associate Minister of Health Peeni Henare said he didn't expect the Whanganui DHB area to hit 90 per cent full vaccination until mid-January.
Henare said it was fundamental that the Whanganui DHB worked to ensure vulnerable communities were vaccinated in an effort to reach that target.
At the moment, 65 per cent of the Whanganui DHB population is fully vaccinated. A further 13 per cent has had one dose of the vaccine.
But the Māori vaccination rate in the DHB region is significantly lower - just 49 per cent is fully vaccinated. A further 16 per cent has had one dose.
Ardern will visit Whanganui and help out at a vaccination clinic in town before speaking to the media.
She will then head to Hunterville to help out at a vaccination clinic later in the afternoon.
Announcing the traffic light system last week, Ardern said regions outside of Auckland could not move to the new system until all had reached 90 per cent vaccination.
That approach would be reviewed by Cabinet on November 29, with Ardern not ruling out amending the requirement of 90 per cent.
Whanganui DHB acting chief executive Graham Dyer said he was confident the DHB would hit the 90 per cent target, but predicting when that would happen was difficult.
"This modelling isn't necessarily a set-in-stone picture of when we will hit the target," Dyer said.
"It's based on a number of variables and trends we've seen so far."
It's understood that Whanganui is expected to be in the group of DHBs such as Tairāwhiti, Bay of Plenty and Taranaki that will be some of the last to hit the 90 per cent target, based on current modelling.
With those who have easier access to a vaccination clinic now predominantly covered, Dyer said the focus now shifts to vaccine-hesitant people or those who, for whatever reason, haven't yet been able to attend a clinic.
"Our focus now is finding those who haven't been vaccinated and ensuring they have the information and resources they need to be comfortable with immunisation," Dyer said.