Family doctors in Hamilton say there's been a rush of people contacting them about a measles outbreak associated with a local secondary school.
Health authorities in Waikato say there have been 52 cases of measles notified so far in an outbreak linked to Fraser High School.
Parents are being urged to check whether their children have been fully immunised, which means a Measles, Mumps and Rubella (MMR) jab at 15 months, followed by a second at four years.
All pupils at the school are being asked to stay home if they have measles, haven't had two doses of the MMR vaccine, or don't know if they are fully vaccinated.
About 200 students and 18 staff are at home and parents are being very cooperative, principal Virginia Crawford said.
Damian Tomic, a Hamilton GP and medical director of the Midlands Health Network, said on Wednesday there is plenty of vaccine available and GPs are keen to get children and adults immunised as soon as they can.
GPs have records and information and will answer questions if people call, he said.
Waikato DHB medical officer of health Anita Bell said no other Hamilton schools are as affected as Fraser High.