Auckland's measles outbreak now stands at 804 confirmed cases.
The number stood at 759 on Friday, and health officials say 18 or 19 people are being diagnosed with the virus each day.
Auckland Regional Public Health Service spokesperson Dr William Rainger says most of the infected are either children or in their 20s.
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The majority of cases are in Counties Manukau, where pop-up vaccination clinics have had a busy weekend.
Counties Manukau DHB's Carmel Ellis told media on Monday afternoon that more than 300 vaccinations have been carried out in the last few days. The Ministry of Health has assured the DHB there are enough vaccines to go around.
School nurses are being upskilled in giving vaccinations, and they will begin administering vaccines to students starting in Manurewa High School on Tuesday. It will take several more days for other nurses to gain the qualification that will allow them to vaccinate.
More than 50 Auckland schools have had confirmed measles cases this year, and a similar number of early childcare centres have had confirmed cases as well.
It's still unconfirmed whether a girl who attended the St Peter's College ball on Saturday night was infected with measles at the time. Officials are waiting on the results of a blood test.
Rainger says even if she was infected at the time of the event (which was attended by students from more than 20 different schools), anyone who caught the virus won't be infectious until this coming weekend, leaving plenty of time to make quarantine plans.
No one has died in the outbreak yet, but Rainger says a child was "very unwell" last week.
He says people need to take measles seriously and get their children vaccinated.
"It's not a trivial illness," he told media. "It can be fatal. It can leave people with permanent brain injuries and can be prevented by MMR. Those are the scientific facts."
He acknowledges some people have concerns about the safety of the MMR vaccine, and wants to reassure anxious parents there is nothing to fear.
"People can be very reassured that MMR is a safe and effective vaccine. People should have no qualms about having themselves and their children vaccinated."
He says those spreading "anti-vax" propaganda are "misinformed and misinforming other people".
"Vaccination is the answer to this."