An estimated 550 health care workers at the Arcadia Family of Cos. were tested this week for the coronavirus in Hawaii’s first mass testing program at nursing homes on Oahu.

The decision for broad testing comes as the Department of Health investigates three positive cases among workers at Oahu long-term care facilities: two at Kalakaua Gardens and one at Maunalani Nursing and Rehabilitation Center.

“We’ve had three cases pop up in long-term care — that can go south really quickly. Many nursing facilities on Oahu share staff, which is a large concern with respect to the spread of COVID-19,” said Suzie Schulberg, president and CEO of Arcadia Family of Cos. — which operates Arcadia and 15 Craigside, which has 590 residents and another 170 home health and adult day care clients. “We have made the decision and commitment to the people we serve to do this and to protect them as best we can because we’ve seen the devastation that’s occurred on the mainland, and it’s heartbreaking.”

Premier Medical Group Hawaii, which has tested roughly 16,000 people at COVID-19 testing sites throughout the islands, conducted the nasal swabbing to detect active virus and has so far found no positive cases.

“We’re screening preventively, not waiting until they’re positive,” said Dr. Scott Miscovich, founder of Premier Medical Group Hawaii. “This is what is happening across the country, and we need to do this throughout the state to protect our seniors and to be screening the communal group-living environments, which could have catastrophic loss of life and overwhelm our hospitals if we let disease spread in these environments.”

The state’s tally of coronavirus cases rose by six — all on Oahu — to 682. There are 44 active infections in Hawaii and 621 patients now considered recovered since the start of the outbreak in February. Hawaii’s death toll from COVID-19 remains unchanged at 17. Of the more than 56,173 coronavirus tests conducted so far by state and clinical laboratories, about 1.2% have been positive.

Hawaii has been successful in keeping the COVID-19 infection rate relatively low compared with the mainland, with no outbreaks in senior living communities and nursing homes, according to the Health Department. The department hasn’t conducted mass testing at these facilities, which have the most vulnerable residents for COVID-19.

“We know it goes against the recommendations of DOH, (but) … it’s the right thing to do,” Schulberg said. “We have a lot of residents, we have a lot of staff who are fearful. COVID-19’s not going away. It will come back, and it could end up in our buildings. We think one of the key ways to see how we can keep COVID-19 out of our communities … is testing. You have to have testing in order to know what’s out there.”

The company has committed to cover the cost of the $130 test for all employees, which equates to $80,000 to $90,000.

While nursing home patients and senior-living residents are not part of the mass-testing program, 55 to 60 individuals who have had symptoms have all tested negative for COVID-19, she said.

“There weren’t a lot of warning signs to say you have active COVID-19 (in the three cases among Oahu nursing home workers),” Schulberg said. “The whole idea of catching an asymptomatic carrier … is very important to us because that’s the silent things that will come in and infiltrate the building and spread COVID-19 throughout. A test could save a life.”