It is not clear whether the four young people struck by measles in recent weeks were immunised, public health authorities say.

This comes as one person remains in Tauranga Hospital following an announcement on Tuesday that there were four cases of measles in the last three weeks, all with connections to the Mount Maunganui area.

The other three people had already recovered when Tuesday's announcement was made.

Toi Te Ora Medical Officer of Health Dr Jim Miller said no further cases have been reported since and it was not possible to provide more specific information on the infected people's whereabouts.

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"All of the recent cases have been in young adults who were staying in the Mount Maunganui area and would have visited many locations over the past few weeks," he said.

He had previously said it was unclear whether the Mount Maunganui cases had any connection with the Christchurch or Auckland outbreak.

Miller said everyone needed to be vigilant and ensure they were up to date with their immunisations, especially the MMR (measles, mumps and rubella) vaccine.

The Bay of Plenty Times asked why the cases were not made public earlier.

Miller said he was informed of a suspected case on April 4 and this was confirmed by laboratory testing late the following day.

Investigation and contact tracing then took place during the weekend and healthcare professionals were alerted to the confirmed case on Monday, with a media statement issued that afternoon, he said.

Miller said more suspected cases were identified during the investigations into the notified case.

If someone suspected a case of measles, Miller urged them to call their GP ahead of making an appointment to avoid potentially spreading the disease in the doctor's waiting room.

As of last week, 67 people were confirmed to have measles in New Zealand this year, including 39 in Canterbury and 12 in Auckland.

One young adult remains in Tauranga Hospital after contracting the measles. Photo / File
One young adult remains in Tauranga Hospital after contracting the measles. Photo / File