The ministry announced today that after a review by Stats NZ, the HSU data would be updated from Monday, August 8, 2022, with a total of 233,000 people on the updated dataset.
The population of Māori on the dataset would increase by 35,000.
But despite the criticism, Old said the HSU was still "ideal" for supporting vaccination efforts.
"It represents real people who are here in the country interacting with the health system," he told a news conference.
"That means that we can target and plan our campaigns at both a community level, for example, identifying areas where coverage is low, but also at an individual level."
In the review, released yesterday, Stats NZ acknowledged inconsistencies in population data, and also confirmed lower representation of Māori.
However, it agreed there were some advantages in HSU's use for health-based analyses, including monitoring vaccine coverage.
"The lower representation of Māori in the HSU requires careful examination at source to identify whether it is driven by systemic issues, or genuine reporting choices by health service users," it said.
Old said the new 2021 dataset would vastly improve Māori data, and the information would now be updated every six months.
The ministry had either already adopted, or was working on implementing all but one of the Stats NZ recommendations, he said.
Old said there was one exception that related to a "technicality" in ethnicity reporting as it was still under discussion with other agencies.