It has a marked ability to spread - perhaps causing some people to believe wrongly that the vaccines aren't effective.
Booster protection against symptomatic infection does wane after several months. But the job of the vaccines is to provide strong protection against hospitalisation and death, not be a barrier to basic infection, and boosters work in that way. Avoiding simple infection requires masks, ventilation, caution and luck, as well as having the doses.
Omicron has reached the very top, touching the Prime Minister and chasing Jacinda Ardern's United States trip, with a key fellow leader, California Governor Gavin Newsom, and Ministry of Foreign Affairs chief executive and secretary Chris Seed testing positive in San Francisco.
Even as New Zealand tries to move on from the pandemic, it reasserts itself.
Here, 80 per cent of the entire population has had two doses and 52 per cent have had a booster.
Offering yet another booster when interest has lagged in the first one may seem futile but isn't.
It should be an opportunity to recapture attention. A publicity campaign could draw in people who weren't interested in a booster shot before. Getting anyone to make a decision to better protect their health is a positive result.
Allowing the problem in our midst to slide in a desire for normality isn't helping to dampen Covid down. Experts fear the low booster rates could make the population more vulnerable for the next wave.
At present, the country is making slight progress in seven-day averages on confirmed cases, hospitalisations and deaths. But it is still heavy going.
There are suffering families behind the huge numbers of infections, hospitalisations and deaths this year. For those stuck with ongoing symptoms, it means a damaging reduction in quality of life.
Simply in economic terms, any chance to reduce sick days from Covid infections over winter and to avoid cases of long-Covid altogether is a saving for businesses and the health system.
Against the background of sluggish progress, casting the booster eligibility net a bit wider might be wise.
So far, the Government has said that the second booster will be focused on at-risk people with legislation planned for June.
Covid-19 Response Minister Chris Hipkins said eligibility criteria would be finalised over the next two weeks. Most people eligible would be able to get it from July.
He said the booster would cover several hundred thousand vulnerable people such as the elderly and those in aged care and disability care facilities. Severely immunocompromised people would also be eligible.
"Based on current advice, for those who are not at risk of severe illness from Covid-19, a two-dose primary course and a booster dose provides very good and lasting protection, which is why we can be more targeted in the rollout of the second booster," he said.
Except that not enough people have already had three doses.
With reinfection likely to become a greater problem over winter, the focus should be on trying to reduce the amount of circulating virus in the community, and promoting boosters widely should help with that.
