A scientist tracking the coronavirus predicts it will keep mutating to avoid the immune response — but at a slower rate than before

• The virus causing COVID-19 probably isn't finished mutating, a scientist tracking it said.
• Mutations might happen less often than before but could help the virus avoid the immune reponse, he said.

The virus that causes COVID-19 will probably carry on mutating but less quickly than it has in the past, a leading scientist has predicted.

Trevor Bedford, associate professor in bioinformatics in the vaccines and infectious diseases division at the Fred Hutchinson Cancer Research Center, said on Twitter Monday that he highly doubted the virus that causes COVID-19, SARS-CoV2, had "hit a wall in terms of its evolutionary potential."

Bedford said that he expected new mutations to help the virus escape the body's immune response, but that these mutations would occur at a slower rate than in 2020.

The highly infectious Delta variant, itself a mutation from the original coronavirus, already has mutated strains, including one called AY.4.2 that doesn't appear to be more dangerous.

Delta became the most common variant in the world within nine months of its first detection, in India in October 2020.

Variants of SARS-CoV2 appeared to "burst onto the scene in early 2021, due to exponential growth." Then Delta, which was more than twice as infectious as the original virus, became the only "virus standing," he said.

"I propose that we're already seeing slowing between 2020 and today," Bedford said.

Delta descendent

Public Health England (PHE) and the Centers for Disease Control and Prevention said in October that they were closely monitoring a Delta-related coronavirus called AY.4.2.

AY.4.2 has been detected in 39 countries and 13 US states, but about 94% of global AY.4.2 is in the UK, according to Outbreak.Info, which is run by the Scripps Research Institute and funded by the National Institute for Allergy and Infectious Diseases.

Dr. Jeremy Barrett, head of the Sanger Institute, said on Twitter Monday that he was "starting to become curious why it has had such a consistent growth advantage in the UK, but has not really increased anywhere else in the world."

It's not yet clear if the virus is inherently more infectious, or if the growth in England is down to characteristics of the population it is spreading in. It accounted for about 11% of Delta cases in England on October 23 and about 15% of cases on November 6, according to PHE.

So far, AY.4.2 doesn't appear more deadly than Delta, and vaccines protect against it, according to the most recent PHE report, released on Friday.

Francois Balloux, director of the genetics institute at University College London, said on Twitter Monday: "I'm personally not overly worried about AY.4.2."