Emails obtained by Newshub show district health board (DHB) bosses are confused about progress with the vaccine rollout because of what they call "ropey" and "really poor" data on the total size of each target group.
The Government says we're ahead of vaccine targets - but health experts say we're guessing.
And when you're jabbing a nation, data is vital. The total size of each group you're targeting, known as the denominator, is a crucial part of the puzzle. Without it, you can't know what percentage has been vaccinated.
But six months into the rollout - we still don't have it.
"It's a major problem. If you don't know the size of the cohorts, then reporting progress against those groups is obviously a guess at best, or could be misleading at worst," says Auckland University Professor of Medicine Des Gorman.
For example, it would be good to know what percentage of family members of border workers have been vaccinated, or the percentage of older Māori and Pasifika people in South Auckland. But we don't have accurate figures for either group, and other groups.
Emails obtained by Newshub under the Official Information Act illustrate the confusion.
Counties Manukau DHB CEO Margie Apa tells her colleagues she can't tell from their data what coverage of groups 1 and 2 they've achieved.
Those groups cover border workers and high-risk frontline medical staff, and older Māori and Pacific people.
In early May, Waitemata DHB Associate Chief Medical Officer and Clinical Director Andrew Old replied saying he can't help as "our denominator data is still really poor, and largely outside our control".
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By late May, Apa tells other DHB bosses `We've lost visibility of coverage of priority groups. I can't see coverage of border workers and their families" and refers to the data as "ropey".
"If your targets are based on estimates and guesses, then in fact it has no integrity," says Prof Gorman.
His colleague agrees.
"We clearly need to have much more precise information, so that we know who we've vaccinated and who we haven't," says Auckland University associate professor of Public Health Dr Collin Tukuitonga.
He says it's not accurate for politicians or the ministry to say they know how we're tracking with each group.
"I think it's an exaggeration."
The Health Ministry says it's trying to get better patient information, but GPs say they have it - they were just never asked for it.
"GPs for their own patient populations, they know the denominators. They know who the patients are that are high-risk, they know the ethnic break outs, they know who to target. It happens every year with influenza vaccine. It can happen now with COVID going forward," says Dr Bryan Betty, medical director of the Royal College of General Practitioners.
He says doctors were not at the table when the rollout began.
"GPs should have been there earlier," says Dr Betty. A survey has shown 60 percent of GPs are willing to help with vaccinations.
Fifteen-thousand people were vaccinated at Auckland's mass vaccination event. But Dr Betty says it's a drop in the ocean.
"The real gains will happen when general practice starts vaccinating their populations across the country," says Dr Betty.
Dr Ashley Bloomfield says the ministry is now going to the DHBs to try to get more specific patient data so they can understand the total size of each priority group.
Newshub asked why they didn't just go to GPs. So far, we haven't had an answer.