Tonga was able to make it two years before experiencing its first COVID-19 outbreak.

About 105,000 people live in Tonga, and its isolated location in the Pacific was helpful in keeping the coronavirus away. Just one case was reported in October, when a Church of Jesus Christ of Latter-day Saints missionary returned home and tested positive while at a quarantine hotel, causing the country to go into lockdown. After making it so long without any outbreaks, the Tongan government was concerned about accepting aid in the wake of the Jan. 15 volcanic eruption and subsequent tsunami, which wiped out villages and contaminated drinking water.

Strict measures were put in place regarding how the aid — including water, medicine, and food — was unloaded from airplanes and ships, but two Tongan men working at the Queen Salote Wharf tested positive for the coronavirus on Tuesday. They are both in isolation. Officials tested 36 people who came in contact with the men, and three tested positive, the Matangi Tonga news site reports. Before learning they had COVID-19, the men went to several public places, the government said, including a church, a bank, and a kindergarten class.

In Tonga, about 61 percent of the population is fully vaccinated. However, since there haven’t been any infections in the country, there is no natural immunity, epidemiologist Dicky Budiman told The Associated Press, and if the shots were given many months ago, they might be less effective. If more and more people test positive, health experts are worried Tonga’s hospitals could become overwhelmed.

“Clearly, when you’ve got countries that have already got a very stretched and fragile health system, when you have an emergency or a disaster and then you have the potential introduction of the virus, that’s going to make an already serious situation immeasurably worse,” John Fleming, the Asia-Pacific head of health for the Red Cross, told AP.