Main coronavirus test produces ‘false negatives’ at least 20% of the time, study shows

Energeticcity is the voice of the Peace.  But we need your help. Give $10 a month today and be the reason we can cover the next story!

The primary type of testing for the novel coronavirus around the world, including Canada, produces “false-negative” results at least 20 per cent of the time, researchers from Johns Hopkins University found.

According to a study published in the Annals of Internal Medicine in May, the false-negative rate of RT-PCR testing used to detect the novel coronavirus changes depending on where a person is in the timeline of the infection cycle.

On day 1 of an infection, the test is completely ineffective at detecting the virus, while on day 8 of infection the test produces false negatives 20 per cent of the time, the study found. The rate of false-negatives then increases every day afterward.

On day five of infection, which is when symptoms of COVID-19 typically begin to appear, and when people are often encouraged to seek out testing, the study found the false-negative rate is 38 per cent.

Story continues below advertisement

“The probability of a false-negative result declines throughout the course of infection,” said Dr. Lauren Kucirka, a resident physician at Johns Hopkins and co-author of the study.

“If you test someone immediately after they’re infected,


Thanks for Reading! is the voice of the Peace, bringing issues that matter to the forefront with independent journalism. Our job is to share the unique values of the Peace region with the rest of B.C. and make sure those in power hear us. From your kids’ lemonade stand to natural resource projects, we cover it–but we need your support.


Give $10 a month to today and be the reason we can cover the next story.

Don't miss any of our wildfire updates

with our daily email!

To help our wildfire coverage, become a Supporter!

This site uses cookies to provide you with a great user experience. By continuing to use this website, you consent to the use of cookies in accordance with our privacy policy.