The island nation of Tonga on Friday reported its first-ever case of COVID-19 after a traveler from New Zealand tested positive.

Tonga is among the few remaining nations in the world that have avoided outbreaks of the virus. Like many of its neighbors, Tonga's isolation has helped keep it safe but it faces big challenges should the virus take hold due to its under-resourced health system.

The nearby nation of Fiji avoided significant outbreaks until April, when the delta variant ripped through the island chain, infecting more than 50,000 people and killing at least 673.

Tonga's Prime Minister Pohiva Tu'i'onetoa said in a radio address that the traveler was among 215 passengers who had arrived on a flight from the New Zealand city of Christchurch on Wednesday and had been isolating at a quarantine hotel.

The prime minister planned on Monday to make an announcement about any future lockdowns, according to news website Matangi Tonga.

Christchurch had been free from the virus for months until this week, when four community cases were reported after a returning resident caught the virus while in Auckland where an outbreak has been growing since August.

New Zealand health officials said the traveler to Tonga was fully vaccinated with the Pfizer vaccine and had returned a negative test before leaving for Tonga. The officials said they would be working with their Tongan counterparts to confirm the case and provide more details in the coming days.

Tongan Health Ministry chief executive Dr. Siale ’Akau’ola said it was unfortunate the plane had already left Christchurch before the news came of the community cases there, Matangi Tonga reported.

’Akau’ola said all frontline workers including health staff, police officers and airport staff who were on duty when the plane arrived had also been put into quarantine after the positive case was confirmed. He added that all those working near the flight had been vaccinated.

Located northeast of New Zealand, Tonga is home to about 106,000 people. About 31% of Tongans are fully vaccinated and 48% have had at least one dose, according to research group Our World in Data.