A new, slightly more contagious mutation of the highly transmissible Delta variant of COVID-19 is beginning to attract attention — particularly in the United Kingdom, where cases are rising again.
The mutation, known as AY.4.2, accounted for six per cent of all new cases genetically sequenced during the final week of September, according to the latest U.K. government data, which also describes it as “expanding” in the country.
The Public Health Agency of Canada confirmed Tuesday that the mutation — which is being dubbed “Delta plus” — has made its way to Canada, with nine cases identified since July.
But experts say while the mutation is worth monitoring, it’s not yet clear if AY.4.2 will become a variant of concern like the original Delta strain.
What is AY.4.2?
AY.4.2 is just the latest mutation of COVID-19, whose spread has led to thousands of variants and mutations as the virus evolves to try and survive.
An offshoot of the Delta variant, it contains two mutations in its spike protein, which allows the virus to penetrate human blood cells. Those mutations, known as Y145H and A222V, have been found in other variants dating back to the earliest stages of the pandemic.
While experts say those spike protein mutations themselves have not led to increased transmissibility in the past, they admit that combining with the properties of the Delta variant could give AY.4.2 an advantage.
“We don’t really know what that advantage is, and hopefully it’s not evading fully vaccinated individuals’ immune systems,” said Stephen Hoption Cann, an infectious disease specialist at the University of British Columbia.
“That’s what we’re most concerned about.”
Francois Balloux, director of the University College London’s Genetics Institute, has estimated AY.4.2 could be up to 10 per cent more transmissible than the original Delta variant.
Comparatively, the Delta variant was found to be twice as transmissible as the original strain of COVID-19, which has Balloux predicting that AY.4.2 “would not have a comparable impact on the pandemic.”
What's happening in the U.K.?
The U.K. Health Security Agency said in a report last week that AY.4.2 is “currently increasing in frequency” among recent cases in England since it was first discovered in July.
The report comes as cases and deaths are rising once again in the U.K., which lifted all remaining public health restrictions — including mask and vaccine mandates — in the summer.
The U.K. recorded 43,738 new COVID-19 cases on Tuesday, slightly down from the 49,156 reported Monday, which was the largest number since mid-July. New infections have averaged more than 44,000 a day over the past week, a 16 per cent increase on the week before.
Also rising are hospitalizations and deaths, which have averaged 130 a day over the past week, with 223 reported Tuesday alone. That is far lower than when cases were last this high — before much of the population was vaccinated. But it’s still too high, critics of the government say.
The health agency’s report said genetic sequencing found AY.4.2 has been detected in six per cent of new cases tested during the week of Sept. 27.
However, Balloux said evidence suggested, “it hasn’t been driving the recent increase in case numbers in the U.K.”
Instead, he and other experts are pointing to both the lifted restrictions and waning immunity in a population that was vaccinated far earlier than most other countries.
The government says it is monitoring AY.4.2 “closely,” but has not yet deemed it a variant of concern or even one under investigation.
Is it in other countries?
AY.4.2 has been detected in very low numbers in the United States and Denmark, which had seen a two per cent frequency before it dropped off.
It has also been detected in Canada, according to the Public Health Agency.
In a statement to Global News, a spokesperson said nine cases were identified between July and late September, adding the agency is also “closely” monitoring the mutation.
Hoption Cann says because AY.4.2 is closely related to Delta — which vaccines have proven effective at stopping at nearly the same rate as the original COVID-19 strain —- the mutation is likely not a threat to vaccinated people.
However, he says more study is needed to know for sure.
“I don’t think this changes what the goal is for countries like ours, which is to get as many people vaccinated as possible,” he said.
“I wouldn’t be surprised if the vaccines offer good protection against this new variant, but that still needs to be determined.”
— with files from the Associated Press