Unvaccinated teachers who turn up at a Canterbury school could be slapped with a $2000 fine.
There are now 28 cases of measles confirmed in the region, with another being investigated.
It is now compulsory for students and staff at Rangiora Borough School to stay away if they aren't immune.
Rangiora Borough School Principal Alan Sutton says they've sent out a notice to all parents. Families of unvaccinated children have also had a direct phone call from him.
"We have advised the parents of 28 unvaccinated children to keep them home. They are aware of the risk, but a couple of kids have come to school."
Sutton says staff are keeping an eye on pupils and any with flu-like symptoms will be sent home.
The school, which has around 560 students, remains open today
18,000 vaccines are due to be delivered to Canterbury doctors this afternoon as waiting lists increase.
The Ministry of Health is reminding anyone who is sick to stay away from work, school or public places, to prevent putting others at risk.