P.E.I. CPHO says many variables can affect outcome of COVID-19 test results

SUMMERSIDE, P.E.I. — A Charlottetown man is questioning P.E.I.’s COVID-19 testing system after receiving multiple negative PCR tests despite testing positive on a rapid antigen test.

David Dougan received a call from his husband on Feb. 28, letting him know he was COVID-19 positive and that he would need to get tested.

Dougan, who works in Victoria, went to the Summerside testing site in Slemon Park, but to his surprise, his test came back negative.

“We looked at each other and we were like, ‘Well how is that possible?’ It just didn’t seem right,” said Dougan in a phone interview with SaltWire Network on March 2. “So, we got our hands on a rapid test the next morning, and my partner is a retired nurse, so he knows how to do a swab. He swabs the back of my throat, he did my nose, and it didn’t take long for it to come back positive.”

With a positive rapid test, Dougan revisited the testing clinic confident he would get a positive. However, the test again came back negative.

Dougan said it wasn’t until his third visit on March 2 when the test finally came back positive. The difference, he said, was how they conducted the test.

“They never did my throat at the testing site,” he said about his previous two PCR tests.

“They did one nostril. My partner swabbed my throat – right down in – and both nostrils. At the testing site, they just did one nostril and, as I say, just tickled the hair.”

On his third visit, Dougan said one of the workers doing the tests had recognized him from his other visits. He said when he told them about the rapid test and the two previous negatives, they did a more thorough swab, which resulted in a positive result.

David Dougan says he visited the Summerside COVID-19 testing clinic in Slemon Park three times before getting a positive test, despite getting a positive result on a rapid antigen test the day of his first visit. - Kristin Gardiner • Journal Pioneer

Higher numbers

Dougan said he thinks the difference in testing methods is likely due to worker burnout from increased testing rates. On March 8, P.E.I.’s chief public health officer said there was an increase of 30 per cent in the number of tests completed last week compared to the previous week.

“My take on it is they are exhausted, it's another day of a thousand people coming through, just swab and go, swab and go all day,” he said. “I know these nurses are exhausted and I feel for them. Hats off to them totally, but I just wonder how many are being missed because (our system) is tired.”

However, while testing numbers have increased, Prince Edward Island’s CPHO said there are multiple factors that could affect the results of a COVID-19 test.

“I think everyone is different in terms of the amount of virus (they have),” she said during a March 8 COVID-19 media briefing in Charlottetown. “When they are exposed to it through, let's say, their nose, it makes copies. How many copies are being made is different for everyone. It also depends on your vaccine status. We tend to see those who are vaccinated, when they are exposed to COVID … their period of time when they are at their most infectious is not quite as spread out as those who are not vaccinated.”

At a glance

• Total RT-PCR tests completed as of March 6, 2022 – 252,132.
• Per cent of tested samples that were positive over last seven days – 25.5 per cent.
• Total cases (including recovered) – 18,905.

Morrison also said other factors that affect testing results include what test is being used, what swabbing method is being used, whether the person being tested is symptomatic and who is doing the test.

“They are not always nurses at our points of entry for instance. That’s why there is sometimes test differences,” she said.

“For those who are arriving and test positive at our point of entry, because it’s a nasal swab and we want to make sure the sensitivity and specificity of the test is more accurate, we actually have those folks get a second test to make sure it's more accurate.”

Morrison said no tests are 100 per cent accurate, and the most accurate tests, the nasopharyngeal PCR tests, are used in places like long-term care facilities where accuracy is key to determining what is happening and if they are in an outbreak situation.

“It scares me to think that people are going with the assumption that they are negative when they (might not be).”

- David Dougan

When it comes to testing discrepancies between tests given at a testing site, such as Dougan’s situation, she said it isn’t surprising.

"We’re doing a lot of tests within a small period of time, so it’s not surprising there may be some examples where there may be some inconsistencies in people,” she said. “In general, if they have symptoms, stay home. Repeat the test if the result is negative the first time and they still have symptoms.”

For Dougan, who wasn’t symptomatic at the time of his tests or when speaking to SaltWire, he still worries many will receive a negative test and return to work or school without considering the possibility they have COVID-19.

“It scares me to think that people are going with the assumption that they are negative when they (might not be),” he said. “I just think of the people who would go, get a negative test and just say, ‘Alright, I’m good.’”

Cody McEachern is a reporter with the SaltWire Network in Prince Edward Island.

Twitter.com/CodyInHiFi