Outbreaks at a pair of Hamilton public schools have been closed after a local lab revealed a processing error tied to false positive COVID-19 tests.
The outbreaks at Lisgar Elementary School and Bishop Ryan Catholic Secondary School, which were declared on Sept. 25 and Sept. 26, respectively, have been rescinded by public health following the discovery of 14 total incorrect test results.
Two of the false positive tests were from individuals at each of the schools. The error was discovered in a “checks and balances” process following the disclosure of the results.
“We sincerely apologize for the impact on those who have received incorrect test results and for the disruptive impact to the schools,” Dr. Marek Smieja, interim chief of the Hamilton Regional Laboratory Medicine Program (HRLMP) said in a release.
In total, seven people declared COVID-19-negative were later discovered to be positive while another seven whose results initially positive turned out to actually be negative after a quality assurance procedure.
Smieja told Global News the lab typically processes around 2,000 tests day and the error was believed to have come from two plates of 96 tests that had seven from each “presumably” mixed up.
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“Obviously we’re trying to improve our processes to understand what happened and how much of this is processing, how much of this is human error,” Smieja said about an ongoing probe into the matter.
All individuals who got the incorrect results have been contacted by a physician and given further guidance, according to the HRLMP.
Public health says it’s following up on the two rescinded school outbreaks through contact tracing and providing guidance to isolate those who received a false negative.
As of Wednesday, Hamilton’s public schools reported a combined 117 new cases in the last 14 days, with 166 in total since the fall 2021 return. Cases among students since the return account for 152 of that total.
There have been five more outbreaks among the city’s educational facilities since Friday in Hamilton tied to 34 cases, bringing the total number of active surges to 11 as of Sept. 28, according to public health.
Since March 2020, the HRLMP has performed more than 762,000 COVID-19 tests amid the pandemic. Hamilton has had 24,519 positive COVID cases.
Smieja said relaying mistaken test results to public health have generally been “not-common.”
The lab did have one other occurrence amid the pandemic in January when multiple incorrect outcomes were sent to the city’s health officials.
Those 31 tests were gathered from Hamilton, Burlington, and the surrounding areas over two days on Dec. 30 and Dec. 31.
Sixteen people who were initially told they were negative for COVID-19 were later informed they were actually positive after the mistake was discovered. The other 15 initially received a positive result but later told they were negative.
“That was a big shock for us because we certainly had processes in place that we were fairly confident would prevent sort of errors of that magnitude,” said Smieja.
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