A NEW COVID-19 (coronavirus disease 2019) variant is spreading in the French region of Brittany, where several patients developed tell-tale symptoms but tested negative for the virus.

Early analysis doesn’t suggest the mutated pathogen is more contagious or causes more severe disease than other versions, France’s health ministry said in a statement late Monday. Experiments are underway to determine the variant’s response to vaccination and antibodies from prior COVID infection, the ministry said.

A handful of patients whose infection was confirmed with samples from blood or deep in the respiratory system had tested negative at first with gold-standard tests, called PCR. Health authorities have increased surveillance amid concern globally about other variants that can thwart vaccines, spread quickly or foment worse symptoms.

The mutation was confirmed by sequencing in eight patients within a cluster of 79 at the hospital in Lannion, in northwestern Brittany, according to the statement. — Bloomberg