Parents at a north Canterbury school have ignored a warning to keep their unvaccinated children at home.

Rangiora Borough School had one confirmed case of measles out of the 25 confirmed so far in the wider Christchurch area.

Its principal asked parents with children who had not had their shots, about 28 in total, to keep them home or get them vaccinated, but on Tuesday about half decided to send them to school anyway.

RNZ asked parents outside the school if they were worried these children might infect their own children.

Rachael Ching supported the school's call for parents to keep their unvaccinated children home and hoped most parents would do the same.

"I can't control anyone else's parenting, just my own."

If her own children were unvaccinated she would take them straight to the doctor and wait until they had their shots.

She was nervous and worried about the fate of children too young to receive the vaccine.

Photo: RNZ

Ayla Ryan had an autoimmune disease and couldn't have the vaccination making her extra vulnerable.

She was taking all the precautions she could to prevent its spread.

"It's mainly spreading [that I'm worried about]. I have friends with small babies. It's just about keeping it contained, so if we can do that by stopping going to public places then we will.

"I won't send my daughter to pre-school until all of the children have had their vaccines so I know I'm not going to pass it on to any child that's there."

She had one daughter at the school but said it was up to individual parents whether they sent their unvaccinated children there.

"They don't need to miss out on education but we need to keep our children safe as well. It's each to their own and I think you can't make people do what you want. We just have to wait until it goes through and hope that we are all ok."

Photo: RNZ

Rachel Knowles didn't think her children had anything to fear from those who had not been immunised.

"My daughter also had the measles at 12 months before she had her MMR injections and she got through that quite fine."

Despite the school's directive, the Canterbury District Health Board said it would not be urging unvaccinated children to stay away from school.

Meanwhile, GPs were largely out of stock of the vaccine and awaiting delivery of a further 18,000 doses.

Pharmac said extra supplies of it would reach the region about midday on Wednesday.

Measles facts: