"We've known that it will be a matter of when, not if, and as we've watched cases appear in other parts of New Zealand. We've always known that at some point this region would see another case.
"I want to encourage people to remember the good protocols we have around masks and scanning. And if you haven't been vaccinated yet, now is definitely the time to get in and get that started," she said.
When asked exactly where in the region the case is, Reese said the ministry is working through a risk assessment and no further details on the case will be provided until then.
As of Saturday, 91 per cent of the Nelson Marlborough DHB had one dose of the vaccine and 83.7 per cent were fully vaccinated.
Reece said the vaccination rate in Nelson is solid but could be better.
"I think we should see 90 per cent as not a target but if we can get beyond that, we start to reduce the risk to our whole community. We've still got room to improve."
Several exposure events are being assessed and any locations of interest confirmed will be published on the Ministry's website.
Meanwhile, five close contacts of a border case announced in Christchurch yesterday are now self-isolating, with testing under way.
The case travelled from Auckland to Christchurch on November 25 on Air NZ Flight NZ8475.
"Anyone who is considered a potential contact of this case will be contacted directly. Unless you are contacted, you are asked to monitor for symptoms, and get tested straight away if you develop any consistent with Covid-19."
People living in Canterbury are also asked to monitor the ministry's locations of interest website.
"Every new case is an urgent reminder to get tested if you're feeling unwell. Testing at high numbers will help to minimise and contain the spread of Covid-19 in Canterbury."