Coronavirus variant found in France could evade PCR nasal swab tests

• The French Ministry of Health has identified a new coronavirus variant that could evade some tests.
• So far, it does not appear to be more deadly or contagious than other strains.
• The variant shares some mutations with another variant first found in California.
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In a region in France, a version of the coronavirus that can be hidden by standard tests has been suppressed.

The French Ministry of Health and Social Affairs announced on Monday that eight patients among a group of 79 COVID-19 cases in Brittany had been infected with the new variant, but several of them tested negative.

Despite these negative tests, the patients showed typical COVID-19 symptoms.

The new variant does not yet have an alphanumeric name. But this is not the first variant that the test can avoid. Finnish researchers announced last month that they had identified a strain called Fin-796H with a mutation that also made it difficult to detect with some nasal swab tests.

An inability to accurately diagnose infected people can make it more difficult to limit the spread of the virus at a time when the cases are already acute.

Confirmation of infections with the new variant is difficult

REUTERS / Gonzalo Fuentes

The standard molecular laboratory tests – known as RT-PCR tests for reverse transcription-polymerase chain reaction – are looking for an infection in a swab from a patient’s nose, looking for the genetic code of the coronavirus.

According to the French health directorate, genetic sequencing has revealed that the variant found in Brittany has several mutations on its peak protein that help it avoid detection by these diagnostic tests.

Health officials in Brittany finally confirmed some of the cases caused by the new variant by testing the patients’ blood on antibodies or collecting samples of mucus, the patients coughed out of their lungs and did so by an RT-PCR test done.

But none of these methods are the typical COVID-19 tests, suggesting that the new variant could spread unnoticed in France and possibly beyond.

However, one European diagnostic company, the Novacyt Group, has Announced Thursday that the PCR tests can successfully detect the new variant.

The variant does not look more deadly or contagious

THOMAS SAMSON / POOL / AFP via Getty Images

According to local outlet LaDepeche, all eight French patients infected with the new variant died of the virus, but local health officials said it did not necessarily mean it was more deadly than other strains.

There is still no evidence that the strain is more transmissible than other versions of the virus. More studies are still needed to determine if it could evade vaccines or antibodies from previous coronavirus infections, the French health ministry said in a release.

The genetic profile of the variant shows that it does not share any key mutations with B.1.351 and P.1 – the variants first found in South Africa and Brazil respectively – which are more contagious and which may partially evade vaccines.

The variant from Brittany is in the same group of strains as a variant first observed in Southern California. Variants in the group, called Clade 20C, are expected to make up a fifth of the world’s coronavirus infections by April, according to Nextstrain, a genetic repository that follows the evolution of the coronavirus over time.

Alain Jocard / AFP / Getty Images

The news about the variant in Brittany comes amid France’s third peak of infections.

The average daily number of coronavirus cases there has doubled since mid-December, jumping from less than 15,000 to an near-record high of more than 38,000 on Wednesday. The increase led to Prime Minister Jean Castex announcing new closures for Paris and the surrounding Ile-de-France region on Thursday.

France has been nationwide for the last two months between 18:00 and 06:00.