Ashley Bloomfield says he has a "really high level of confidence" the Omicron variant can be kept out of the country over summer, but won't be afraid to play "aces" if it gets in.
New Zealand recorded its first case of the highly mutated strain of the SARS-CoV-2 virus on Thursday - a person in managed isolation and quarantine (MIQ) who arrived in Christchurch from Germany (via Dubai and Auckland) about a week ago.
It's still early days, but the evidence to date suggests Omicron is far more infectious than Delta and is able to get around immunity offered by both vaccines and natural infection.
"I'm not sure if there will be further [positive] tests from that flight, but what I would say is this will be the first of many Omicron cases we will see at the border," the Director-General of Health told Newstalk ZB on Friday morning.
"We saw this with the Delta variant. It started off with the first, then a few cases, but then as it became the dominant variant - that seems to be what's happening in Europe, where Omicron is really surging - we will see and we're expecting that most of our cases within a short period of time will be Omicron coming across the border. We will deal with them and keep them at the border - that's our aim."
He said hundreds of Delta cases had been stopped at the border, with just the one leak so far - causing our current outbreak.
"The key thing here is at the moment we have our very strict and rigorous border measures in place, that most countries don't have - and we will be keeping those in place, Dr Bloomfield told RNZ in a separate interview on Friday morning.
Earlier this month the Government ditched the alert levels systems in favour of the COVID-19 Protection Framework, which doesn't have lockdown restrictions built into it. But they remain an option.
"Even under the COVID-19 Protection Framework, there is still provision for localised or regional lockdowns if that's needed - even without Omicron - to control the number of cases if we've got high rates of infection in an area," he told RNZ.
"Of course, the key thing as we've found right through this pandemic is keep as many aces in your hand as you can, and don't be afraid to play them when you need to."
Asked how likely it was a lockdown might be needed, Dr Bloomfield said it was "not possible" to say yet.
"We don't have it in the community as yet, which is good, and we're going to do everything we can to keep it that way."
Deputy Prime Minister Grant Robertson told Newstalk ZB the arrival of Omicron in MIQ was cause for concern, but not panic.
"Our whole MIQ system has been set up to deal with a very transmissible variant in the form of Delta. We have an MIQ system that many other countries around the world don't… while it's not 100 percent perfect, it's served us very well."
He said the system was under constant review, and changes might be made to handle Omicron to prevent a repeat of the Delta outbreak.
The gradual reopening of the international border which starts in January - at first to fully vaccinated Kiwis - might need to be postponed too.
"We're looking at the developments internationally every day and making sure we're giving the best possible advice," said Dr Bloomfield. "I know that there will be reconsideration of that just to see how things are in early January."
Robertson shut down talk of banning arrivals from the UK, which has set new infection records two days in a row this week - likely thanks to Omicron. He said arrivals are already required to be double-vaccinated and have a negative pre-departure test.
"That to me is what you do… that's the process we've got. It's pretty thorough, it's much more thorough than most other countries in the world."
