Nunavut mine workers with presumptive cases may have had COVID-19 before, says top doctor

The two presumptive cases of COVID-19 at Nunavut's Mary River Mine have tested negative, according to the territory's chief public health officer.

The cases were announced on July 15. Chief Public Health Officer Dr. Michael Patterson said at the time that the individuals were asymptomatic. He said the two people, and their contacts, were immediately placed in self-isolation.

A news release Wednesday confirmed the negative results.

Officials said the swabs were sent to a lab in the South for confirmation and the results came back Tuesday, Patterson said.

"At this point, neither the test cases nor the contacts have developed symptoms that are consistent with COVID-19 and there is no evidence of transmission at the mine site," Patterson said in the statement.

The Mary River Mine is located about 176 kilometres southwest of Pond Inlet.

Baffinland Iron Mines — which runs Mary River — had said the possible transmission of the virus didn't occur on site, and was the "result of a localized southern cluster."

This is the second time a presumptive case was announced at the mine this month.

A presumptive case of COVID-19 was reported there on July 2. The territory said on July 10 that the test came back negative after it was sent to its accredited lab in Ontario.

3 people could have had COVID-19 before: top doctor

Patterson told CBC that the three mine workers who had presumptive cases of COVID-19 could have had the illness before, but recovered.

He said the people who were recently tested will continue to self-isolate, "because in this case ... we don't have solid confirmation that they had an infection in the South."

It's the nature of the beast in dealing with this illness.- Dr. Michael Patterson, Nunavut chief public health officer

Patterson said the mine's initial swabs were retested in Iqaluit using the GeneXpert, and one tested positive. All of the results sent to the Ontario lab came back negative, he said.

Patterson said there are a number of reasons why the tests keep producing different results. He said it's an ongoing issue for other jurisdictions — not just Nunavut.

"This is a common issue around the world. It's just much more obvious for Nunavut because we have no active cases."

He said the timing of the swabs, swabbing techniques to the back of the nostrils, and varying machine sensitivities are all factors why some machines test positive and others negative.

"Unfortunately there's no medical test in the world that is always going to be 100 per cent reliable," he said.

Patterson said the repeated negative results of the presumptive cases are not a bad reflection of the tests done at the mine, in Iqaluit nor the South.

"It's the nature of the beast in dealing with this illness," he said.