The Government denies accusations it has "sneakily" changed the vaccination rollout dates after wording on the Ministry of Health's website was altered.
On the Unite Against Covid-19 website, which provides estimates on timeframes for the staged vaccine rollout by priority group, the wording for Group 4 has been changed from "being vaccinated from 28 July" to "they will be able to book their vaccinations from 28 July".
It comes after the Ministry was accused in May of quietly changing the timeline on when the general public will be vaccinated from "from July" to "from the end of July", without publicising the change.
Covid-19 Response Minister Chris Hipkins recently admitted to the Herald the Government "could have been clearer" in its communications over the rollout.
The Ministry did not answer questions about when the latest change occurred, and why it was not publicised.
A spokeswoman said the wording was "updated" to make it "absolutely clear that people aged over 60 can book their vaccination from 28 July, as they are eligible to do so from that date".
There was no change to the programme's rollout, she said.
Book My Vaccine was also scheduled as planned to go live on July 28.
Act Party leader David Seymour said the original language would make "anyone think there would be needles in arms on that date".
"The Government has once again sneakily changed the dates that vaccines will be available.
"This is classic slipperiness from Chris Hipkins. He promises us one thing, realises he can't deliver, changes the words slightly and then denies anything has changed.
"There clearly won't be vaccinations happening for Group 4 on the date we were promised, and he owes us an explanation."
A spokesman for Hipkins said the change in language "does not signify anything untoward".
It was an acknowledgement that saying the group would start from a certain date set an expectation everyone could be vaccinated straight away, when in it was always going to take a period to get through the group, he said.
"The change in language reflects and responds to that. It does not suggest a delay, more that it will take a period to get through everyone. The start date remains the same."
The first age band in Group 4 is people aged 60 years and over, who will be able to book their vaccinations from July 28.
Bookings for people aged 55 and over will open on August 11 and depending on supply and progress invitations will open up to people over 45 years from mid to late August, mid to late September for people 35 plus, with everyone else being eligible from October.
The Government has been under pressure over its vaccine rollout, with the per capita vaccination rate placing New Zealand at 122nd in the world.
Text messages for vaccination bookings were also sent out to people thought to be in group 3 but who were actually in group 4.
Many people over 65 years old have also been frustrated at being unable to get vaccinated, while more than 50,000 people in group 4 have been able to get their first jabs.
Hipkins told the Herald last week the Government could have made it clear to those in group 3 that most of them wouldn't get vaccinated until the second half of the year.
"We certainly could have been clearer right from the beginning that it is going to be a three or four-month process."
He has repeatedly explained the pace of the rollout as being entirely dependent on Pfizer for the timing and quantity of shipments.
New Zealand's current vaccine stocks are expected to run close to zero by Tuesday, when a shipment of 150,000 doses is scheduled to arrive.