Scientists worldwide are closely tracking a descendent of the highly infectious Delta variant that is spreading in the UK. In a briefing from the Health Security Agency, released on Friday, “a Delta sublineage newly designated as AY.4.2 is noted to be expanding in England”, with the body adding that the variant is being monitored and assessed.
According to Business Insider, Francois Balloux, director at the University College London Genetics Institute, said on Twitter on Saturday that data about AY.4.2 suggested it could be 10 percent more transmissible than the most common Delta variant in the UK, called AY.4.
The report states that in the week beginning 27 September – the last week for which complete sequencing data was available – AY.4.2 accounted for about 6 percent of sequenced coronavirus cases and is “on an increasing trajectory”.
AY.4.2 contains two mutations in its spike protein, called A222V and Y145H. The spike protein sits on the outside of the coronavirus and helps the virus to enter cells.
Former U.S. Food and Drug Administration Commissioner Scott Gottlieb, MD, also tweeted about a new Delta subtype over the weekend.
Dr. Gottlieb also followed up with a Tweet, adding: “The variant has been in the UK since about July, but it has been slowly increasing in prevalence. There’s no clear indication that it’s considerably more transmissible, but we should work to more quickly characterize these and other new variants. We have the tools.”
He also offered this bit of perspective: “This is not a cause for immediate concern but a reminder that we need robust systems to identify, characterize new variants. This needs to be a coordinated, global priority for Covid same as similar international efforts have become standard practice in influenza.”
However, Dr. Jeffrey Barrett, the director of the Covid-19 Genomics Initiative at the Wellcome Sanger Institute in Cambridge, along with Prof. Balloux, while agreeing the new variant may be 10 to 15 percent more transmissible than the original Delta variant, still urge caution.
“Britain is the only country in which it has taken off in this way and I still would not rule out its growth being a chance demographic event,” Balloux said. He also told The Guardian the new variant was unlikely to be behind the recent rise in cases.
“Its potential higher transmissibility could at this stage only explain a tiny fraction of additional cases,” he said. “It’s around 10% frequency [now], and assuming it may be 10% more transmissible, that would only explain an additional 1% extra infections [every five or so days].”
Ravi Gupta, a professor of clinical microbiology at the University of Cambridge, told the Guardian these mutations were not of particular concern. “A222V has been seen in other lineages of Delta,” he said. “It doesn’t have a really large effect on the virus.”
Gupta says scientists are “missing the point” by focusing solely on the new variant. “We shouldn’t be blaming the virus for what is going on in the UK,” said Gupta. “It is because we have fundamentally failed to control transmission, and that is because kids are vulnerable, they have not been vaccinated, they are back at school, they are spreading the virus among themselves and they are feeding it into their families.”
Further talking about the Delta variant, Gupta added: “It breaks through the vaccines anyway, so vaccines protect you partially from an infection being transmitted but it is not complete protection,” he said. “So the message needs to be, let’s stop worrying about mutations and worry about the fact we have an uncontrolled transmission in the UK.”