A Bay of Plenty man is furious he could be a potential Covid-19 carrier despite following all the advice given to him when he arrived back from Melbourne to Auckland 12 days ago.

Ross Dempsey returned from working in Melbourne on May 20 and was told he was not required to get a Covid-19 test because of the travel free arrangement between Australia and New Zealand.

Since then, the 52-year-old fitter welder estimated he has been in contact with up to 200 people, including friends and workmates.

Then last night Dempsey received a call from the Ministry of Health telling him to self isolate and get a test. It was the first contact he had received from the MoH about it.

After a receiving a Covid-19 test this morning he promptly booked himself into an Air BnB in Mount Maunganui where he plans to self isolate and wait for his test result.

But Dempsey felt it was all "too little too late".

"As of yesterday I was sitting in a smoko room with 40 other people at a job. Prior to that I've been visiting family and friends since I've been home. It's just a joke."

He had been on the flight with about 22 other contractors he knew and as of Tuesday morning believed only a quarter of them had been contacted.

The group had been working more than two hours away from Melbourne and had not visited any of the locations of interest.

Dempsey said he did have a "little bit of a dry throat", but put it down to working in a dusty fertiliser plant.

However, the Ministry of Health says the risk of community transmission from Melbourne is low despite the number active Covid-19 community cases reaching 52 and it is likely its current lockdown will be extended.

At the end of last week the Ministry of Health updated its advice to travellers who had returned from Melbourne, requiring them to self isolate until they returned a negative test.

The Ministry's contact tracing team emailed around 5000 people who had travelled from Melbourne between May 20 and May 25 and instructed them to get a test and self-isolate at home or in the accommodation they are staying in until they have a negative result. It also instructed them to contact Healthline if they need further advice or to report if they had been at a location of interest.

About 500 of those 4539 people were unable to be reached by email were followed up with phone calls and texts and as of this afternoon the ministry had contacted all but five travellers.

A Ministry of Health spokesperson said its contact-tracing teams had worked hard to actively communicate with travellers around the recent outbreaks in Melbourne.

More than 90 per cent of people were contacted within 24 hours of the self-isolation and testing requirement being enforced.

"With just five people still to make contact with, we'd like to thank travellers for their co-operation as we've worked to provide them with the latest information in an evolving situation."

The public health requirements (including isolation/quarantine and testing) for travellers who were in Greater Melbourne between May 20-25 was "precautionary" and the risk to the New Zealand community from these travellers was considered low, they said.

Anyone who has been in Victoria since May 11 also needed to keep checking the Victorian government website as locations of interest were continually being added. Those who had been to a location of interest people could call Healthline on 0800 358 5453 for further information.