VANCOUVER -- The union representing longshore workers at the Port of Vancouver says three of its members have tested positive for COVID-19, and it's voicing concerns about the possibility of more workers contracting the coronavirus from international vessels arriving in Metro Vancouver.

Local 500 of the International Longshore and Warehouse Union - which represents workers at the Vancouver terminal - says the three workers who tested positive contracted the virus around two weeks ago, but they worked shifts in the jurisdiction of Local 502 - which represents workers at Deltaport - before they developed symptoms.

The workers who tested positive are now self-isolating at home, and the union has asked members who were exposed to the virus to isolate and monitor themselves for symptoms.

At the same time, the union is expressing concern about a vessel that arrived at Deltaport last week.

Two crew members aboard the Sofia Express - an international container ship registered in Germany - have tested positive for COVID-19, and five more are isolating while they wait for test results.

Patrick Bolen, first vice president of ILWU Canada, told CTV News Vancouver pilots at Deltaport objected strenuously to allowing the ship to dock there.

"We all felt it should be quarantined until everybody is cleared and through the incubation period," Bolen said. "We had a conference call where all the stakeholders were involved, and at the end of the day it was a 30-minute conversation that went nowhere."

Local pilots brought the ship into Deltaport early Saturday morning, after it had spent most of the week moored offshore, according to Bolen.

He said discussions with Global Container Terminals led to extensive cleaning, restrictions on the movements of the Sofia Express crew and conversations that would normally be done in-person being had by phone instead.

Before those discussions, union members had been considering refusing work because of health and safety concerns, Bolen said. Work began on the Sofia Express Saturday night, he said, but added the union is still worried about the potential for future issues.

"We're still concerned," he said. "If this happens again, you know, our problem is we're kind of the front end of the food chain, the whole supply chain."

Bolen said the incident has been something of a wake-up call for the union.

"It was one of the first ones that came in with a positive test," he said. "You know, we berth a lot of vessels, and our concerns, I think, were reasonable. And all we wanted to hear from (our employer) is they were being answered to."

With files from CTV News Vancouver's Nafeesa Karim 

Correction:

A previous version of this story referred to Patrick Bolen as the first vice president of the ILWU Local 500. He is the first vice president of ILWU Canada.