Rapid test very reliable when used on symptomatic patients, Quebec scientists find

·3 min read

Microbiologists in Quebec City say they have found a way to reliably use a COVID-19 testing kit that can deliver accurate results in 15 minutes, but only when used on symptomatic individuals.

The ID NOW test was approved by Health Canada earlier this year, but the agency recommended confirming results with a standard laboratory test because its detection rate was only 75 per cent.

That prompted Quebec to delay using ID NOW kits at testing sites in the province, preferring the more sensitive PCR lab test that can take several days to analyze.

But a pilot project run by the CIUSSS de la Capitale-Nationale and CISSS de Chaudière-Appalaches — regional health authorities in the Quebec City area — has increased the rapid test's reliability by only using it in certain conditions.

When used on patients with clear COVID-19 symptoms and an elevated viral load, the scientists were able to raise the detection rate to 98.8 per cent.

Jeff Chiu/The Associated Press
Jeff Chiu/The Associated Press

According to infectious disease specialist Jean Longtin, what's key is to "ensure to use the right test for the right patient, at the right time." He says effective triage at testing sites would allow the rapid tests to be used reliably.

"The larger the viral load in the patient's respiratory tract, the better the performance of the test," said Longtin, who added those conditions mean it wouldn't be effective for screening travelers at airports.

Rapid tests could speed up contact tracing, experts say

A senior public health official in Quebec City said patients with clear symptoms of COVID-19, and who live with others, would be eligible for the rapid test.

That represents roughly a third of the 1,000 people who show up daily at the testing site at the ExpoCité convention centre in Quebec City, said Serge Garneau, assistant director of general health services for the CIUSSS de la Capitale-Nationale.

Garneau said the pilot project shows that the second validation is no longer necessary. The CIUSSS is planning on recommending that the ID NOW tests be used on their own, under specific circumstances.

The convention centre currently has six rapid testing kits, but is hoping to receive 40 more by the spring.

Millions of rapid tests have already been delivered to provincial health authorities across Canada. In Quebec, they are being used in Saguenay and at Maisonneuve-Rosemont Hospital in Montreal.

But in nearly all cases, the tests are verified with a PCR test due to questions over the reliability of rapid testing.

The biggest advantage of an accurate ID NOW test is speeding up the contact-tracing process, which is vital to controlling the spread of the disease.

"It will allow us to move faster than the virus and find the person's contacts in an hour or two, instead of waiting 24 hours," Longtin said.

Performing the ID NOW test remains a complicated process, however. Specialized swabs and equipment are needed to use them correctly, and each testing kit can only process four tests per hour, one test at a time.

Ottawa has provided Quebec with two kinds of rapid tests: the ID NOW test, as well as one developed by Panbio. Both are made by Abbott Laboratories.

According to documents obtained by Radio-Canada, the Panbio tests present more significant reliability problems than the ID NOW tests, missing 20 to 30 per cent of positive cases.

A similar pilot project is underway to determine if the reliability of the Panbio tests can also be increased.