France investigates Brittany variant of coronavirus that ‘hides in tests’

A new variant of the SARS-CoV2 coronavirus has been detected in Brittany that fails to show up in PCR tests

Credit:  DAMIEN MEYER/AFP

France is investigating a new “Breton variant” of the coronavirus found in the western region that is proving harder to detect in PCR tests.

Little is known about the first regional mutation found in France though for now nothing suggests it is more contagious or dangerous.

The variant Breton was pinpointed by a hospital biologist in Lannion, a city on the English Channel, who had studied dozens of recent deaths.

Samples sent to the Pasteur Institute in Paris for genetic sequencing confirmed it was a previously unknown variant of the virus that has killed more than 90,000 people in France.

Testing and tracing efforts have been stepped up in response to determine if the variant has spread to other regions, said Stephane Mulliez, director of the regional ARS health service.

In particular, scientists want to understand if the variant can evade detection after seven of the deceased patients delivered negative PCR tests and returned a positive result only from samples taken from blood or deep in the respiratory system.

All of the patients were elderly and had underlying health risks, said Mr Mulliez.

"One possibility is that the virus spreads more quickly between the upper respiratory tract and the lower portions," Alain Tertre, a regional director of the national Sante Publique France health agency, said at a press conference.

Investigations are underway to assess the Breton strain's transmissibility and severity

Credit: DAMIEN MEYER/AFP

As it is harder to detect, the ARS has added it to the WHO’s list of variants under investigation (VUI). However, it is not currently in the more worrying variant of concern (VOC) category.

"Initial analysis… does not suggest increased danger or contagiousness compared with the original virus," the ARS said in a statement.

For now only the British, Brazilian and South African variants are on the VOC list, out of hundreds that have been discovered by researchers worldwide.

France is now in a “sort of third wave” due to the prevalence of the three variants, prime minister Jean Castex told MPs on Tuesday.

Paris in particular has seen cases rise to more than 400 per 100,000 amid speculation President Emmanuel Macron could impose a weekend lockdown in the French capital in the coming days.

French health authorities on Tuesday said there were 4,239 patients in intensive care units for Covid-19, up by 20 over 24 hours and setting a nearly four-month high.

The total number of people hospitalised for the disease rose by 23 to 25,492.