The Ministry of Health has changed its advice again on how long to wait between doses of the Pfizer vaccine, and COVID-19 Response Minister Chris Hipkins insists it's nothing to do with supply.
Director-General of Health Dr Ashley Bloomfield in August increased the time between first and second doses from three weeks to six weeks, which he said was "in line with other international programmes".
He assured people at the time that "if you have already been fully vaccinated with two doses less than six weeks apart, as we have been doing, you will have very strong protection against the virus and do not need to doubt that".
But on Thursday, the Ministry of Health changed the gap between doses again, this time returning to the original three-week gap, in what it described as a push to get people fully vaccinated quickly, as COVID-19 spreads beyond Auckland.
The changing advice comes at a time when the Government is trying to convince vaccine hesitant people to trust their guidance. But Director of Public Health Dr Caroline McElnay says it should not cause alarm.
"We sought advice from our Technical Advisory Group on this particular issue because a number of health professionals have said to us, at this moment in time when we really want to get as many people as possible fully vaccinated, can people be vaccinated before six weeks?" Dr McElnay said on Wednesday.
"The Technical Advisory Group has come back and said yes, there never was any safety concerns with vaccinating at three weeks, and so from a pragmatic, practical perspective, at this moment in time, if you've had your first dose and the only thing that's stopping you from getting your second dose is waiting for a six weeks mark, the advice is that can be done sooner."
The international advice on how long you should wait before getting a second dose varies. The World Health Organisation (WHO) recommends an interval of three to four weeks between first and second doses.
But in July, researchers in the UK found that an eight-week gap seemed to be the sweet spot for tackling the more transmissible Delta variant.
The researchers found that extending the time between the first and second doses of the Pfizer vaccine boosted antibodies against all variants of the virus tested compared to a short dosing interval.
Until May, the UK had imposed a 12-week gap between doses, in order to prioritise first doses for as many people as possible with limited vaccine supplies, the same way the gap was extended in New Zealand in August to allow more people to get the jab.
COVID-19 Response Minister Chris Hipkins denies the extension had anything to do with the fact that vaccine supply was much lower in August than it is now. The bulk of vaccines arrived in New Zealand this month.
"No, it certainly wasn't because we were running out of vaccines, although it did allow us to vaccinate more people more quickly, and that was an upside of it," Hipkins said.
"But that was not the only consideration there. It was a consideration amongst many, yes, and I think we were quite open about that at the time, that it was one of the things we considered.
"We make these decisions based on the advice that we get from the Technical Advisory Group. Their advice at that time was to move to six weeks. Their advice now is to three."
Dr McElnay said there's no magic number - it just needs to be a minimum gap of three weeks, which is supported internationally.
The minimum gap between doses recommended by manufacturers and public health experts is 21 days for the Pfizer vaccine, and 28 days for the AstraZeneca and Moderna vaccines.
"It's a range," said Dr McElnay. "The Technical Advisory Group has advised us that yes, people can get that vaccine as many others have, so long as you have the three-week gap. That is the bit that is fixed - the three-week gap between doses."
According to data published on Monday in the Lancet medical journal, the effectiveness of the Pfizer vaccine in preventing infection by COVID-19 dropped to 47 percent from 88 percent six months after the second dose.
With half of the eligible population of New Zealand fully vaccinated and more than 80 percent with at least one dose, the Government desperately wants to reach the remaining 20 percent who have not yet received one dose.
