CANBERRA, Australia (AP) — The Australian navy's largest ship docked at disaster-stricken Tonga on Wednesday and was allowed to unload humanitarian supplies in the South Pacific nation despite crew members being infected with COVID-19, officials said.

Nearly two dozen sailors aboard the HMAS Adelaide were reported infected on Tuesday, raising fears the mercy mission could bring the coronavirus to the small archipelago devasted by an undersea volcanic eruption and a tsunami on Jan. 15.

Since the pandemic began, Tonga has reported just a single case of COVID-19 and has avoided any outbreaks. It’s one of the few countries in the world currently completely virus free. About 61% of Tongans are fully vaccinated, according to Our World in Data.

The 27,500 metric ton (30,300 U.S. ton) ship had completed the 3,300-kilometer (2,050-mile) voyage from Brisbane and would deliver supplies without contact with the local population to avoid infections, the Australian government said in a statement.

“We appreciate the decision of the government of Tonga to enable HMAS Adelaide to dock and offload the humanitarian and medical supplies, and the high priority it has placed on COVID safety throughout the recovery process,” the statement said. “The ship is undertaking an entirely contactless delivery of humanitarian assistance and disaster relief supplies.”

With restoration of the drinking water supply a major priority, the ship brings a desalination plant. It's also carrying helicopters and engineering equipment.

Australia said it was widening its disaster support to include restoration of power and communications.

Tonga usually requires visitors to quarantine for three weeks on arrival and the tough pandemic measures complicate the international disaster response. All international aid is to be delivered without local contact.

Tongan authorities have been wary that accepting international aid could usher in a bigger disaster than the huge eruption of the volcano. The tsunami has claimed three lives.

The ship is the second aid mission from Australia in which at least one crew member tested positive. A C-17 Globemaster military transport plane was earlier turned around midflight after a person aboard was diagnosed with the coronavirus.