New Zealand should soon be receiving a delivery plan from Pfizer, which could determine the speed of the Covid-19 vaccination rollout for the general population.
It comes as the Government's Covid website changed the wording for the general population rollout, from July, to the end of July.
Covid-19 Response Minister Chris Hipkins stressed the start times had always depended on delivery times of vaccines.
"Supply has always been a factor that is going to play a big role in determining how fast we move with any of those groups," he said.
Hipkins said the rollout to "group three", the group most at risk of becoming very sick from Covid-19 had begun, "but we simply won't have enough vaccines" by the end of June to cover the entire group.
"That means when we start group four (the general public) we will still be having the bulk of group three to do."
He said the general public would be likely to be waiting "a little bit longer" for their vaccine.
On if he was concerned about vaccine supply, Hipkins said New Zealand had not yet received a confirmed delivery schedule from Pfizer for after July 1.
"We know what we're getting between now and the end of June. Our model very much works to that."
He said Pfizer had been "pretty straight up" in the way it was handling the process and were committed to honouring the contractual agreement it had with New Zealand and other countries.
Hipkins thought it could be about a week before the delivery schedule would be received.
"We're expecting within early June, the first week of June, to get an understanding from Pfizer of what's happening post-July. We’re in the same position as a lot of other countries.
"It may mean we have to slow down a little bit at the beginning of July to make sure we don't get into a position where we run out. If we're not getting a reasonably sizeable delivery early in July."
Hipkins said the agreement with Pfizer was that it would deliver New Zealand all the vaccines needed for the vaccination programme between July and September, "but the delivery schedule hasn’t yet been completely confirmed".
He added it could be "well into July" before people would have clarity of when they could specifically get their vaccine.
Dr Bloomfield also announced today people added into group three include people with severe mental illness, people who have hypertension that is not well controlled with medication and those who are severely obese.
He also encouraged those with coughs and colds should not go about their daily business, instead they should still isolate and ring Healthline for advice around getting a test. Dr Bloomfield also urged people to keep using the tracer app.
"It is important everyone takes up the offer of being vaccinated when their turn arises in the coming six months, as we roll out the vaccine to a further three and a half million people," he said.