One of the key issues New Zealand will have to be prepared for if the Omicron variant gets into the community here is that a lot of people will get sick, quickly, at the same time.
That's the pattern happening overseas right now.
This would likely cause problems here for workers falling ill and businesses needing adequate staffing. It wouldn't be just in the health sector but across the board.
In the United States, where cases have soared with the arrival of Omicron, health officials advise that members of the public who test positive should stay home and isolate for 10 days.
In the UK, the Guardian reports that more than 600,000 people would have been isolating this Christmas weekend with Covid. In July the UK economy suffered a dip when many people had to self-isolate when Covid infections surged.
Case numbers are steaming upwards in Australia across several states, especially New South Wales. So far the hospital figures for severity are steady.
The extra contagiousness of Omicron is a counterbalance to better news from scientists that people infected with this variant are less likely to need hospital treatment. That's based on data from South Africa, Denmark, England and Scotland.
Major caveats are that outbreaks in younger people in this early data could skew the results - when older people with other health issues are most at risk - and that the sheer volume of infections could strain health systems. It will also be a few weeks before the impact on hospitals is clear.
The reduction in severity overall is thought to be due to Omicron's greater ability to make people ill who have been vaccinated or previously infected. But most of the breakthrough infections and reinfections so far are considered mild - potentially unpleasant but not requiring a hospital visit.
Overall, the new data reinforces the need for vaccine and booster protection. Unvaccinated people are still most at risk from Omicron and Delta.
On Friday the UK Health Security Agency found that people with Omicron are between 50 and 70 per cent less likely to need hospitalisation than those with Delta.
It said that protection from a booster against basic Omicron infection starts to wane after about 10 weeks, although protection against severe outcomes would likely last for longer.
Imperial College London researchers said there's an estimated 20 to 25 per cent less likelihood of any trip to a hospital compared to Delta.
South Africa's National Institute for Communicable Diseases found that suspected Omicron cases were 80 per cent less likely than Delta cases to be admitted to hospital. Once there, Omicron and Delta cases had the same likelihood of becoming serious.
The figures from Denmark showed that Omicron cases were three times less likely to require hospital treatment.
Omicron may turn out to be a hard-punching variant - striking fast and then falling away as it is in South Africa - rather than a persistent scrapper like Delta that hangs around.
Evidence overseas so far suggests Omicron has a wide reach, and may catch people in New Zealand who had few problems dodging Delta. And Omicron would be a challenge for our test and trace system.
Unlike in Europe, there's little immunity here acquired from previous infection so vaccine and booster levels need to be as high as possible.
Confusion over exactly when people could get their booster shots after the border changes were delayed has been an unnecessary muddle.
Clear messaging about using top quality masks indoors in shops and working from home if possible to avoid transmission would be important in an Omicron outbreak.
And the standard practices of being outside or in a well-ventilated place, and keeping a distance when near others are still valid.