Throughout Wednesday's White House COVID-19 Response Team briefing, Centers for Disease Control and Prevention Director Rochelle Walensky verified that the subvariant has been detected 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 stated. "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 been 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 detected for the first time in Israel in an 11-year-old boy who entered the nation from Moldova, Israel's Channel 12 News reported.
The boy was flagged at the airport and sent into quarantine, according to The Times of Israel.
Health officials announce there is no proof 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.
"U.K. 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 U.K. 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 intended to hold a meeting on the subvariant amid concerns that the new strain could change the nation's fading infection numbers.
In Israel, 1,486 new infections were reported on Monday and another 701 late Tuesday.
A spokesperson for British Prime Minister Boris Johnson announced that the government was keeping a "close eye" on the AY.4.2 variant, though 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.
An October 15 report by the U.K. Health Security Agency, the AY4.2 variant accounted for close to 10% of all sequenced cases in the nation. But Cohen said the fact that it is 10% more transmissible needs to be put into perspective.
"This is not a catastrophe, compared to the other variants we have known," he said.