Coronavirus: Expert calls for border reopening to be postponed, fully vaccinated to be redefined

A COVID-19 modelling expert is calling for plans to open up travel from Australia to be "immediately postponed", and the definition of fully vaccinated changed to mean those with three vaccine doses, not two. 

Sticking to the current reopening plan and traffic light system - which depends heavily on people being 'fully vaccinated' - could easily result in our biggest outbreak yet, says David Welch, a computational biologist at the University of Auckland. 

"Omicron is globally the fastest spreading variant we have seen. Multiple countries - including those with very good surveillance such as South Africa, Denmark, UK, Australia - are seeing large and rapid outbreaks where the doubling time for daily cases is about two-three days, which means that 10 daily cases can become 10,000 daily cases in less than a month."

South Africa, where the variant was first spotted, is recording 50 times as many cases a day now than it was a month ago. And experts in the UK are warning the country's current daily infection figures - already the worst since the pandemic began - could be dozens of times higher as soon as Christmas if measures aren't taken to halt Omicron's spread. 

Daily infections in New Zealand have trended downwards since the move to the 'traffic light' system, which gives people more freedoms if they're vaccinated. But Auckland is one of the most highly-vaccinated regions of the country, and from Wednesday, residents have been allowed to travel to less-protected areas. 

The current outbreak here is the Delta variant, which though more infectious than previous strains, still struggles to get through vaccine protection - the heavily mutated Omicron, not so much.

US researchers on Friday reported protection against Delta from mRNA-based vaccines starts to wane as early as three months after the second dose, the decline accelerating after four. 

And an Israeli study published earlier this week found by six months, protection against Omicron was basically gone. 

"If you're past five months and didn't get a booster, go get it," Gili Regev-Yochay, director of the Infectious Diseases Unit at Sheba, told reporters. Israel began its vaccine rollout much earlier than most other countries, so trends are often picked up there first. 

And new data out of Australia - where daily case numbers are rapidly increasing - suggests antibodies from vaccination are between two and 20 times weaker against Omicron than previous strains of COVID-19, resulting in a drop in protection against symptomatic infection to 40 percent, and against severe disease to 80 percent (down from the mid-90s). 

"This is concerning because lab-based neutralisation correlates with protection from infection and suggests that current two-dose vaccine regimens will not protect against Omicron infection," said Fran Priddy, executive director of Vaccine Alliance Aotearoa. 

Other studies overseas looking at both lab and real-world outcomes have had similar results. 

"All these countries where we are seeing rapid spread have high levels of immunity already, either by vaccination or due to previous widespread outbreaks," said Dr Welch. 

Vaccine manufacturers have said they're looking into making Omicron-specific vaccines. But there is good news in the Australian research - a booster of the original vaccine formulation can significantly help.

"A booster dose with an existing mRNA vaccine… has the potential to raise efficacy against Omicron to 86.2 percent against symptomatic infection and 98.2 percent against severe infection," the research, published online ahead of peer review, said.

The Government announced in November that from January 17, fully vaccinated Kiwis - that is, double-dosed - will be able to come home from Australia without having to go into managed isolation and quarantine (MIQ). From February 13, they'll be able to arrive from anywhere without MIQ. 

New Zealand passed the 90 percent double-vaccination threshold for those eligible on Thursday. But Dr Welch says three doses should be the minimum for people arriving from overseas, especially while we don't have any known spread of Omicron here.

"Keeping it out requires ongoing maintenance of the MIQ system for all arrivals into the country, whether vaccinated or not. With rapid spread in Australia, the plan to allow NZ citizens to return with no MIQ from January 15 should be immediately postponed to provide certainty to those affected. 

"The vaccination requirement for arrivals should be raised to three doses of the vaccine to reduce the risk of Omicron coming here."

There's even the chance Omicron is much more rampant overseas than official figures suggest. 

"In an ongoing evolutionary twist, there are two distinct lineages of Omicron," said Mike Bunce, genomics expert at the Institute of Environmental Science and Research.

BA.1 can be identified via a simple PCR test, which BA.2 can't.

"BA.2 might be flying under the radar," said Dr Bunce, urging officials to exercise caution when deciding to loosen restrictions. 

"Even if Omicron (or another variant) result in half the hospitalisation rate, twice as many infections will place the same net demand on the hospital system."

With UK experts suggesting there might now be "two epidemics on top of each other" - Delta and Omicron - Dr Bunce suggested this could result in a mutant combo virus with the worst of both strains.

"Using genomics, there remains a lot of scrutiny of Omicron and Delta including the possibility of the variants 'merging' (in a process known recombination) which can occur if infected with both variants at the same time."

Fran Priddy, executive director of Vaccine Alliance Aotearoa, said the Ministry of Health should bring forward the booster campaign - currently double-vaccinated people have to wait six months before getting a booster. But as most of us only got our second doses in the past few months, if Omicron gets here sooner rather than later, we'll be at greater risk. 

"Until we understand how pathogenic Omicron may be (ie how deadly) it is critical to complete two-dose vaccinations, accelerate the booster campaign, and also to consider whether the six-month booster interval should be shortened."

Newshub asked the Ministry of Health whether there are plans to shorten the wait on Wednesday morning, but despite following up, is yet to get a response.