Just around half of a currently eligible 1.5 million Kiwis have received their booster dose. Photo / AP
Just around half of a currently eligible 1.5 million Kiwis have received their booster dose. Photo / AP
Boosting millions more Kiwis now could spare New Zealand a much worse Omicron peak weeks from now, a top epidemiologist says.
Several experts have today urged the Government to follow several Australian states and cut eligibility for a booster to three months after peoples' second dose - arguing Omicron's arrivalhas made the move an urgent necessity.
More than half of around 1.5 million currently eligible New Zealanders have received their booster, which is estimated to restore protection against symptomatic disease by up to 70 per cent.
According to the Herald's Vaccine Tracker, some 2,935,467 people - or nearly 70 per cent of the over-12 population - have received two doses only.
Director-general of health Dr Ashley Bloomfield said the four-month wait would stay in place for now, but added the Government was keeping the option of a shorter gap under advisement as it reviewed evidence.
Booster uptake rates for people over 65 were currently high around the country, he said, and health workers were moving through those in the early-vaccinated group three as quickly as possible.
"And all of our district health boards are positioned to have all our aged residential care people with their boosters by the end of this month."
Otago University epidemiologist Professor Michael Baker, however, said boosters for the bulk of Kiwis needed to be made available right now.
"If we follow the same curve that's been seen everywhere else Omicron has been encountered, we will have a very intense epidemic that may peak in as little as six weeks from now," he said.
"We need to be rolling out interventions as fast as we can, because now is the time when we can have the biggest impact on that curve and how steep it is."
Given it took around two weeks for the booster to rebuild its best immune response, Baker saw little reason not to get the third shot out to more people now.
"The booster will have very little value if it arrives late," he said.
"Much of its advantage is to help dampen down the outbreak wave, because it means people suddenly have a lot more antibodies, and they're a lot less likely to pass the virus on."
Odette and Nick Waanders, and Bronwyn and Doug Goldfinch, wait their turn for their booster jabs at Hawke's Bay's Rangitane clinic this month. Photo / Dave Murdoch
Baker argued that, even if the evidence around a three-month booster's effectiveness was still emerging, "we can just consider basic infectious disease epidemiology – that is, we won't get much benefit from it if it's delivered once the epidemic is starting to peak".
Based on overseas experience, Covid-19 modellers have warned of a peak that could number more than 10,000 daily case numbers – even with interventions and high vaccination rates.
University of Auckland senior lecturer Dr David Welch echoed Baker's call.
"I'd say that evidence from overseas Omicron outbreaks shows that we can go from the early few cases to extremely widespread outbreak within weeks," he said.
"If we want to use the time advantage we have with low Omicron cases, now is the time to act.
"If people have to wait for four months for the booster, many may not even be eligible for the booster until the peak of the outbreak or later."
University of Auckland epidemiologist Professor Rod Jackson also wanted the interval shortened.
"That should happen today. I think it's absolutely crazy leaving it at four months, as we've got a huge number of people who have only received two doses only."
UK data has suggested the Pfizer vaccine's effectiveness against symptomatic disease with Omicron dwindled to only 10 per cent just four months after the second dose – reflecting the fast-spreading variant's heightened ability to evade immunity from vaccines or prior infection.
Infectious diseases expert Associate Professor Siouxsie Wiles said what data she'd seen around booster effectiveness and time intervals came with a large amount of variation between people.
"We also don't know is whether supply is an issue. There are also a lot of people who are eligible and not taking it up, so I'd hope that they do that."
Otago University immunologist Associate Professor James Ussher said New Zealand needed to get its booster rates up as quickly as possible.
"For those who are unvaccinated, it is not too late to get vaccinated and they should do so ASAP," he said.
"A move to red is sensible and will help slow transmission of Omicron, enabling administration of boosters and primary vaccination courses and reducing the impact on our health system."
