London lab adds new equipment to boost COVID-19 testing capacity

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By pooling samples, the lab can turn around results for about 6,000 COVID-19 tests each day compared to 3,500 daily tests if they run samples through one by one. The lab, which completed its first COVID-19 test in March, had a year-end goal of 7,200 daily tests.

The pooling method only works in areas where there is a low incidence rate of COVID-19 and a low percentage of tests coming back positive, Kearns said.

If the panel of four samples is run through the test process and turns up negative, the testing is complete. If the panel turns up a positive, each of the four swabs are re-tested individually, Kearns said.

In a region where there is a high percentage of tests coming back positive, pooling samples does not make sense, Kearns said.

“As the percentage of positivity grows, then you get to a tipping point where you’re actually doing extra work. If a high percentage are turning up positive, then you have to retest all four individually,” Kearns said.

With the new equipment arriving early next month, the lab will be able to churn out results for 7,200 tests if it runs the samples through one-by-one or more than 10,000 if it pools samples.

The pooling method is just as accurate as running tests individually, Kearns said.

“We wouldn’t be satisfied with anything less. That’s the benefit of having a team that is highly skilled medical microbiologists on our team that can guide us through the science,” Kearns said.

“We’re one of the first in Canada to be doing that pooling strategy and it’s served the region incredibly well in terms of optimizing the equipment we have, adding capacity and (improving) turnaround.”