A subvariant of the delta mutation previously seen in the United Kingdom has been found in the U.S. and Israel, health officials said.
During Wednesday's White House COVID-19 Response Team briefing, Centers for Disease Control and Prevention Director Rochelle Walensky confirmed that the subvariant has been found in the U.S., though not in clusters.
"In the United States, delta remains the dominant variant with more than 99.7% of sequence cases in the country being caused by delta," Walensky said. "There are new variants that continue to emerge as cases continue to spread, and in particular, the AY4.2 variant has drawn some attention in recent days.
"AY4.2 is a sublineage of the delta variant that has recently identified in the U.K., and we have, on occasion, identified the sublineage here in the United States but not with recent increased frequency or clustering to date."
The subvariant was found for the first time in Israel in an 11-year-old boy who entered the country from Moldova, Israel’s Channel 12 news reported.
The boy was flagged at the airport and sent into isolation, The Times of Israel reported.
Health officials say there is no evidence yet that the new strain is causing an uptick in coronavirus cases in some places.
Former United States Food and Drug Administration Commissioner Scott Gottlieb on Sunday called for research into the subvariant.
"UK reported its biggest one-day [COVID] case increase in 3 months just as the new delta variant AY.4 with the S:Y145H mutation in the spike reaches 8% of UK sequenced cases," Gottlieb tweeted. "We need urgent research to figure out if this delta plus is more transmissible, has partial immune evasion?"
Walla News reported that Israel's Health Ministry officials planned to hold a meeting on the subvariant amid fears that the new strain could reverse the country's fading infection numbers.
In the U.K., COVID-19 infection rates have remained stubbornly high, despite high rates of vaccination. Nearly 50,000 new cases of COVID-19 were recorded Monday.
In Israel, 1,486 new infections were reported on Monday and another 701 by late Tuesday.
A spokesperson for British Prime Minister Boris Johnson said the government was keeping a "close eye" on the AY.4.2 variant, but said there was no evidence it spreads more easily.
"As you would expect, we are monitoring it closely and won’t hesitate to take action if necessary," he told reporters, the Times of Israel reported.
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