A new sub-lineage of the highly contagious Delta variant that is currently spreading throughout the UK has now been detected in the United States, health officials said Wednesday.
AY.4.2 is being closely monitored in the UK after British health officials revealed the new variant — reported to be 10-15 percent more transmissible that Delta — had been linked to a growing number of COVID-19 infections there.
Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, confirmed during a COVID-19 briefing Wednesday that AY.4.2 had been found in the US.
Walensky said the new variant, which she acknowledge had “drawn some attention in recent days,” has not been linked to any clusters within the country.
“We have, on occasion, identified this sub-lineage here in the United States, but not with recent increased frequency or clustering to date,” Walensky said.
“At this time, there is no evidence that the sub-lineage AY.4.2 impacts the effectiveness of our current vaccines or therapeutics and we will continue to follow.”
She added: “In the United States, Delta remains the dominant variant with more than 99.7% of sequence cases in the country being caused by Delta.”
A CDC spokesperson told the Post that AY.4.2 is “very rare” in the US – with “less than 10” cases found so far, which accounts for less than 0.05 percent of sequenced cases.
The CDC has not confirmed what US states AY.4.2 has been detected in.
Former U.S. Food and Drug Administration commissioner Scott Gottlieb tweeted about the variant over the weekend, calling for “urgent research to figure out if this delta plus is more transmissible” or has “partial immune evasion.”
Experts told the UK’s Financial Times that AY.4.2 appeared to be 10 to 15 percent more transmissible than the original Delta variant.
British health officials said last week they were closely monitoring AY.4.2 after the latest data showed six percent of COVID cases in the country were linked to the new variant.
AY.4.2 has not been labelled as “under investigation” or a “variant of concern” in the UK.
Experts said there was no early indication that AY.4.2 would become the dominant variant and that it was unlikely to change the current COVID picture.
“Discovery of new variants is of course important to monitor, but it doesn’t indicate that that new variant is going to be the next one to replace Delta,” Oxford Vaccine Group chief Andrew Pollard told BBC radio on Wednesday.
“Indeed even if it does, Delta is incredibly good at transmitting in a vaccinated population and a new one may be a bit better but it’s unlikely to change the picture dramatically from where we are today.”