Hundreds of people have been offered a third Pfizer vaccine following a botch up at the Highbrook Vaccination Centre in South Auckland in July.
On July 12, 731 people went to get a vaccination at the centre, however an end-of-day reconciliation of vaccine doses did not match up with the number of vaccines given out.
Health officials later revealed that potentially up to five people may have received a diluted dose on that day.
Months after the incident, a letter from the Northern Regional Health Co-ordination Centre, which 1News has seen, was emailed last night to the hundreds of people affected, offering a third vaccine jab.
“After an extensive investigation, unfortunately we cannot determine who may have been affected," the letter read.
"The Ministry of Health has recommended that all those who attended for vaccination at Highbrook on 12 July are offered the choice of a third 'extension' dose of the Covid-19 vaccination."
It said that the patient's GP would have to give consent to the third dose.
"The Pfizer/BioNTech Comirnaty Covid-19 is not approved for a third dose in New Zealand."
The letter also repeatedly states there is little evidence around the risks - if any - of having a third jab.
Daniel Metcalf, one of the 731 people who attended the Highbrook Vaccination Centre on July 12, described the situation as "frustrating".
He said it had taken too long to receive information about what the next steps were for those caught up in this.
"It's been two months and I've had just as many letters."
Dr Bryan Betty, medical director at the Royal New Zealand College of General Practitioners, said it was not unusual for a GP to prescribe an un-approved medication.
"One of the issues that's arisen here is that the third dose hasn't been approved for use in New Zealand by Medsafe. When that situation arises, you do need consent to be given the medication," he said.
"It's part of the normal process that occur when we don't have a regulatory approval to give the third dose in this country."
He said he would recommend anyone offered the third jab to seriously consider it.
"There's certainly no problem or additional problems with having a third vaccine at this point."
The Northern Regional Health Co-ordination Centre's clinical director, Anthony Jordan, told 1News the letters were sent following advice sent from the Ministry of Health and range of experts.
"We have provided those who attended the centre that day with a comprehensive range of information and have encouraged them to speak to a medical professional, such as their doctor or one of our Healthline professionals, to help them to make an informed decision," he said.