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French coronavirus variant can’t be detected by PCR tests

Coronavirus French Mutation

We’ll need coronavirus vaccine booster shots for the foreseeable future to ensure continued protection against COVID-19 as the novel coronavirus mutates. That’s what Sharon Peacock, the head of COVID-19 Genomics UK (COG-UK), told Reuters earlier this week. The scientist leads researchers whose job is to sequence as many coronavirus strains as possible and assess risks. The coronavirus mutates about once every two weeks, and three variants are currently of concern.

The B.1.1.7 mutant from the UK is more infectious and deadly than progenitors, but responds well to vaccines. The South African (B.1.351) and Brazilian (P.1) strains can reinfect COVID-19 survivors and reduce vaccine effectiveness. Peacock said that she was primarily worried about the South African variant, warning that there might be other variants out there they haven’t even discovered.

The French health ministry just confirmed Peacock’s prediction, announcing the discovery of a new coronavirus variant on Monday. The new strain doesn’t appear to be more transmissible or more serious than others, but it does have one unexpected ability: It seems to be undetectable with current PCR tests.

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The health ministry said that the new variant was found in a cluster of eight cases in a hospital in Lannion in the French region of Brittany, France 24 reports. But several of those cases had not been detected via PCR tests. Per Bloomberg, the authorities sequenced samples from eight patients from a bigger cluster of 79 at the hospital.

The PCR test is the standard for diagnosing COVID-19. It’s been used from the early days of the pandemic, with the world having now reached a point where people can get tested with relative ease. Quick antigen tests are also available, but PCR tests are the primary diagnosis tool for COVID.

It’s unclear why the Brittany version of the coronavirus has been able to avoid detection. Such a development is worrying if this strain were to be highly infectious, as existing coronavirus tests might not pick it up. The virus could continue to spread undetected. PCR tests can be updated to continue detecting new strains, but the new kits would also have to detect existing strains.

French officials said that researchers at the Institut Pasteur are already analyzing the genetic changes that might have allowed the French mutant to avoid detection.

“Investigations will take place to determine how this variant reacts to vaccination and to antibodies developed during prior COVID infections,” Brittany’s regional health authority said in a statement.

Even without a PCR test to pick up the illness, the symptoms COVID-19 patients might show could be enough for clinicians to suspect an infection with the novel coronavirus. Genetic testing would confirm the presence of the virus, although they would take longer than PCR.

The following video briefly explains how PCR testing works so well in diagnosing COVID-19. The test targets specific gene segments particular to SARS-CoV-2 to deliver a positive diagnosis. If the French variant has suffered genetic changes at all the gene sites that the PCR test covers, test results could deliver false-negative results. The UK, South African, and Brazilian variants each feature several distinct mutations, so it’s possible the French strain might also have a few distinct genetic changes.

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Chris Smith has been covering consumer electronics ever since the iPhone revolutionized the industry in 2008. When he’s not writing about the most recent tech news for BGR, he closely follows the events in Marvel’s Cinematic Universe and other blockbuster franchises. Outside of work, you’ll catch him streaming almost every new movie and TV show release as soon as it's available.