The Whānau Ora Commissioning Agency will consider taking its case to the High Court, Waitangi Tribunal or the Human Rights Commission should the Ministry of Health refuse to share vaccination data for 5 to 11-year-olds.
The agency has waited more than a month after first requesting the data to get a headstart on preparations for the rollout to children under 12, which began on January 17.
It was the latest development in the data-sharing saga between Whānau Ora and the Ministry of Health, which saw the former take the latter to the High Court twice before the desired data was shared - giving Whānau Ora more information on unvaccinated Māori in the North Island.
The Ministry of Health confirmed it had received Whānau Ora's request but because of the information's sensitive nature, would consult various stakeholders on the approach to sharing personal information about tamariki.
Whānau Ora chief executive John Tamihere told the Herald the agency made an informal request for data on under-12s in December, thinking that would be sufficient given data-sharing agreements had been signed between the two entities.
However, according to Tamihere, the ministry responded in the first week of January, requesting a formal application for the data.
A completed application was sent back to the ministry within 24 hours, Tamihere said.
Since then, Whānau Ora had heard little - other than that the ministry was "going through their process".
"That's what they've said and I've asked my people to chase up on it and the emails we get back [say], "We are going through our approval processes'," Tamihere said.
Tamihere wouldn't rule out taking the matter further if the data wasn't shared.
"We don't rule out any of our remedies, either going to the Human Rights Commission, back to Waitangi Tribunal or the High Court.
"That's a determination we will make when our facts are on point to win the next case."
Tamihere said it was essential as many vaccinations were administered as possible to ensure Kiwis were protected before winter.
Ministry of Health national immunisation programme director Astrid Koornneef said previous High Court rulings did not consider the sharing of personal contact information and vaccination status of tamariki.
Given the sensitivity of the information, Koornneef said the Ministry would seek guidance from various parties about how the data could be shared.
"The Ministry will consult Māori leaders, stakeholders and service providers, including Whānau Ora Commissioning Agency, as well as the office of the Children's Commission and Privacy Commissioner about the approach to sharing personal information about children," she said.
"The Ministry has always been open to discussions with Whānau Ora, iwi, and other key groups about ways to strengthen the roll out of the vaccination programme to Māori, including the recently launched vaccination programme for 5-11 year olds."
It comes after the Herald revealed significant inequities in Auckland's childhood vaccination rollout.
Data obtained by the Herald showed 3485 of the 24,628 Māori aged 5 to 11 in Auckland have been vaccinated (14.2 per cent) to Monday, January 24.
The level for Pasifika was almost identical at 14.4 per cent - 4407 of 30,713 Auckland Pasifika children have had one dose.
For children of other ethnicities in Auckland, 32.5 per cent had received a vaccination - 33,384 out of 102,680.
The data did not specify vaccination levels for ethnicities other than Māori and Pasifika.
Overall, 26.1 per cent of Auckland's 5-11 population had received a dose - 41,276 out of 158,021.