Nelson Marlborough has recorded 15 cases of Covid-19 on Wednesday, the highest daily total yet in the Omicron outbreak.
Of these cases, 13 are in Nelson Tasman and two are in Marlborough.
New Zealand recorded 1160 new community cases across 17 different regions on Wednesday.
It comes as three Nelson schools have been forced to send students and teachers into self-isolation after positive Covid-19 cases attended the schools.
Nayland College, St Joseph's School and Victory Primary School all have people isolating.
Nelson Marlborough has a strong uptake of childhood immunisation with 46 per cent of those aged between five and 11 at least partially vaccinated, NMH medical officer of health, Dr Stephen Bridgman, said on Tuesday.
"However as schools have started back we have seen a sharp decline in the number of children presenting for immunisation.
"While children and young people are less likely to become seriously ill, some will become very sick and need to go to hospital," he says.
“We know that we cannot stop Omicron. The escalation of cases in Nelson over the past two days shows how quickly it can spread and how disruptive it can be to workplaces and schools. It also shows how prepared education and workplaces are in supporting employees, students and communities through Omicron."
He says anyone with Covid-19 symptoms should be presenting for testing, even if they are vaccinated.
Community testing stations are in place in Nelson and Blenheim.
