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COVID-19 tests in Ontario can pick up false positives

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Dr. Ian Gemmill, acting medical officer of health for the Northwestern Health Unit, said in a press release on Tuesday the tests that they are using in Ontario are extremely sensitive, which means it can pick up all the true positives, but also some false positives as well.

Yesterday, a new case was announced through a post on Facebook belonging to the Rainy River First Nations. However, a follow-up update was released saying that after review, the case was found to be indeterminate. The test was repeated to get a conclusive result.

“When we hear a reported positive, we have to look into them very carefully before we actually call them cases,” Gemmill said. “This is really important because of not only the working details but also the disruption this causes to people who may have been in contact. The NWHU does not announce cases or add them to the list unless we are absolutely 100 per cent sure that they are true positives. We have to be sure we are dealing with a true positive because false positives are possible.”

The update also stated that the Fort Frances Tribunal Area Health Services have been in direct communication with all community members that may have had close contact.

Fort Frances Tribal Area Health Services confirmed that they have been in communication with the individual and has initiated contact tracing. According to health officials, contact tracing helps reduce the risk to the community and the public. Close contacts include anyone who had close physical contact, within two metres and for more than 15 minutes.

“We do get reports of positives from time to time that we need to look into very carefully to find out whether they are true positives or not,” Gemmill said. “It is really important to be able to say with certainty that a positive is correct or not. Even if it is 99.99 per cent accurate, if they are testing a million people in the province, there are thousands that could pass a false positive. We take every single case that comes out and we investigate it very thoroughly to see where we are.”

Over 7,500 tests have been carried out in the northwestern region. About 6,000 of those are negative with 22 resolved cases and three active ones.

Positivity rate becomes lower and lower because the positives are going up more slowly and the testing is increasing, so the nominator is rising quite faster in this case, Gemmill said.

The government of Ontario began lifting up its second stage of restriction last Friday. This means more public gatherings can be held as long as all participants are observing physical distancing measures.

“We can have things in the patio as long as the groups together social distance,” Gemmill said. “Although we don’t have a lot of cases here, we still need to physical distance. Despite the fact that we got some relaxation now, we still need people to be smart about this and to continue doing the things that we are recommending all along.”

When it comes to travel, the approach has not changed much. However, Gemmill said he is suggesting people postpone travel unless it is for essential purposes.

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