Morrinsville College is in the middle of trying to prevent a measles outbreak.
The Waikato school will be closed until Tuesday, and even then students will only be allowed back in if they can prove they've been vaccinated.
Any students or teachers that haven't had two vaccinations must stay home for at least 14 days from their last known contact with students.
This is the second measles outbreak this year. In February, an infected man entered SkyCity Auckland and the exclusive SugarTree apartments after ignoring incubation requests.
Actions against measles seem drastic, so what actually is it?
A viral disease, measles is extremely infectious and can result in hospitalisation if not treated.
Most people are immunised as infants, but for those who haven't, or are concerned for their health, here are a few tips on what to look out for and how to avoid it.
How is measles spread?
Measles can be spread via coughing or sneezing and through contact with mucus.
When will symptoms appear?
It usually takes around 10 days for symptoms to appear.
What are the symptoms?
Fever, a runny nose, a cough and sore red eyes initially, and then a blotchy, red rash beginning on the face which spreads in the coming days, are common symptoms.
The Auckland Regional Public Health Service recommends those who might be infected stay away from public areas and get medical help immediately.
How serious can it be?
Some people with measles may suffer pneumonia, an infection of the lungs, or encephalitis, swelling of the brain. Up to one in 20 children with measles develop pneumonia.
It can lead to hospitalisation and death.
How can you prevent measles?
The only way to prevent measles is to get the MMR vaccine.
A single dose given at 12-15 months will provide immunity for over 90 percent of recipients, a second dosage lifting that to 95 percent.
The vaccine is free for children and adults.
People born before 1969 when the vaccine was introduced may also be immune, but it is worth getting checked.
Overseas travel increases risk
Those who travel outside of New Zealand who are not immunised pose a risk of bringing the infection home.
Anybody travelling abroad should make sure they are immunised before leaving.
In February 2016, a man infected with measles entered SkyCity Auckland and the exclusive SugarTree apartments, ignoring incubation requests from health officials.
On April 12, 2015 a person diagnosed with measles visited several public places in south Auckland.
A 15-month-old travelling from Taranaki contracted measles while overseas and returned to New Zealand via Auckland on November 2, 2014. All passengers were advised to see their GP.
In 2011, a provisional total of 222 measles cases were reported from 31 states across the US.
Worldwide there has been resurgence in measles which started in Europe, a common destination for Kiwis. More than 30,000 cases were notified in both 2010 and 2011.
In 1991, New Zealand was hit with an epidemic. There were 10,000 reported cases, but health experts estimate around 30,000 or more were infected. Six hundred were hospitalised, and seven died.
In 1997 2000 people were infected and 300 hospitalised, but no deaths. A mass immunisation campaign followed.
What is the measles, mumps, and rubella (MMR) vaccine?
The MMR vaccine is a free injection that immunises people against measles, mumps and rubella.
It is given in two doses, normally at 15 months and at four years, which give more than 95 percent protection.
However, when there has been a rise in measles cases it is recommended that all children from age 12 months who have not had one dose of MMR should receive it is as soon as possible.
The vaccine is also given to older children and adults it was missed when they were younger.
Everyone born from January 1, 1969 should have had two doses.
How effective is the MMR Vaccine?
More than 90 percent of people are protected with one does. This increases to 95 percent if people have two.