As of mid May, 82 per cent of adults in the Pacific country had received at least one vaccine dose, with 75 per cent fully vaccinated.

The Omicron variant has also "spread rapidly" through affected islands, says Vanuatu's ministry of health.

With some natural immunity and vaccination rates being what they are, authorities are happy to re-open to tourists on July 1.

But Director General of Health Russel Tamata admits vaccination rates differ between major centres and more remote areas.

The logistics of cold chain management, distance to fixed health posts and reduced availability of healthcare workers all factor in.

"The geographical nature of Vanuatu, with 83 Islands scattered across an archipelago 1300 kilometres long, makes it quite challenging to co-ordinate a vaccination effort," Mr Tamata said.

"On top of that, access to some villages in remote islands is quite difficult with access via boats only and no road access."

To reach some of the far-flung islands, the former Australian cruise boat has been transformed into a medical response vessel, complete with cold chain storage.

At least five cabins were ripped out to create space for necessities like a vaccine preparation room and storage area.

Fridges resembling those in Australian hospitals have been hard-wired so an alarm triggers if any part of the cold chain breaks down.

Australian social enterprise Respond Global is working with Vanuatu ministry officials to deliver the rollout, with private funding from a philanthropist.

The ship has already been tasked with carrying urgent supplies of oxygen bottles, fuel and other medical equipment from a DFAT donation to the island of Pentecost, site of the most recent COVID-19 outbreak, Respond Global founder Ian Norton says.

"The vessel then moved to Luganville to prepare for deployment up the west coast of Santo.

"Also called the Weather Coast, this remote area has little or no road access and very rarely has received medical support over the last two years."

The return of international tourists is generally seen as positive but there is concern over the pace of the vaccine rollout within the country.

"They're worried they haven't had a chance to vaccinate everybody, particularly in those outer islands," Dr Norton said.

"Some villages are saying, 'Where the hell have you been? Why weren't you here months ago?' and immediately have mobilised the entire village to come down and take part."

But enthusiasm can shift depending on the area and there are patches where vaccine hesitancy persists.

Local and provincial teams will help guide the operation.

"The provincial groups actually generally know which areas have had problems and have some hesitancy, and we take a much slower approach there," Dr Norton said.

"They're in a much better position, they've got the local language (and) local cultural experience that we could never have."

The four-month program will cover the country's six provinces and include 63 permanently-inhabited islands, starting in low-coverage areas.

The ship, HELPR1, will also carry local experts in specialist areas like eye health, ear, nose and throat, dental, primary care and non-communicable diseases like diabetes.

As part of the program's legacy, HELPR1 will remain in Vanuatu for use in ongoing local response delivery in the Pacific.

"This ship will be vital for our national health teams to reach our hard-to-reach areas, especially for COVID vaccine coverage before our borders reopen," Vanuatu Health Minister Bruno Leignkone said.

Australian Associated Press