Scientists are monitoring a new COVID subvariant spreading in the UK that could be more contagious than ​Delta

A new coronavirus subvariant that could be more contagious than the Delta variant has begun to spread in the U.K. — and scientists around the world are taking notice.

What are the details?

In a report issued last week, the U.K. Health Security Agency noted that AY.4.2, a descendant or sublineage of one of the Delta variants, has started to spread in the country and is now under "monitoring" status.

While data so far on the new subvariant is sparse, U.K. scientists said the viral strain "accounted for approximately 6% of all sequences generated" and was "on an increasing trajectory" in the week beginning Sept. 27.

According to BBC News, AY.4.2 was first discovered in July and had been slowly increasing since then, up until a few weeks ago, when the new subvariant's trajectory rose signififcantly.

In a tweet thread posted on Saturday, University College London Genetics Institute Director Francois Balloux indicated that the subvariant may be 10% more contagious than the most dominant Delta variant, called AY.4, which erupted like wildfire across the globe during the late summer months.

"As such, it feels worthwhile keeping an eye on it," Balloux noted, though he added that early indications show AY.4.2 to be only "marginally" more transmissible than its parent strain.

"It's nothing compared with what we saw with Alpha and Delta, which were something like 50% to 60% more transmissible," he told BBC.

What has been the reaction?

At this juncture, most scientists are in agreement with Balloux that the subvariant is not a cause for panic.

The new strain has not yet been elevated to a "variant of concern" status by the U.K. government, and in other places where it has been found — such as in Denmark and the U.S. — it has not shown a notable upward trajectory.

But everyone seems to agree that further testing and continued monitoring are needed.

Dr. Scott Gottlieb, who served as the commissioner of the U.S. Food and Drug Administration under former President Trump, acknowledged that the strain is likely not a "cause for immediate concern," but called for "urgent research" to figure out if it is more transmissible or has partial immune evasion.

"We should work to more quickly characterize these and other new variants. We have the tools," he tweeted over the weekend. "This needs to be a coordinated, global priority for Covid same as similar international efforts have become standard practice in influenza."

Dr. Jeffrey Barrett, a director of the COVID-19 Genomics Initiative at the Wellcome Trust Sanger Institute in Cambridge, tweeted that AY.4.2 is the only Delta descendent "steadily increasing," which suggests it has a "consistent advantage" over other strains.

Why does it matter?

The new data could be a fluke and the new subvariant's spread could fizzle, but it's worth pointing out that data out of the U.K. in the late spring foreshadowed the Delta variant's eventual spread in the U.S. months later.