AY.4.2 Detected in 32 States As U.K. Declares Variant Under Investigation

The AY.4.2 COVID variant has now been detected in over 30 U.S. states, with 130 cases reported in the country overall.

The variant has caught scientists' attention over the past couple of weeks due to its sharp rise in the U.K. in recent months.

It is thought that AY.4.2 might have some sort of growth advantage over other Delta variants.

AY.4.2, an offshoot of the Delta AY.4 variant, currently accounts for between 11 and 12 percent of recent U.K. COVID samples and 21,848 cases had been reported there overall on Monday morning EDT.

The spread is not as rapid in the U.S, though the majority of states have reported at least one case.

The state with the most AY.4.2 cases, as of Monday morning EDT, appeared to be Colorado, with 18. Florida followed with 17, and then Washington with nine, according to the variant tracking tool Outbreak.Info. At least one case has been reported in 32 states altogether, the database showed.

It comes after AY.4.2 was recently declared to be a Variant Under Investigation on October 21 by the U.K. Health Security Agency, which had been assessing the variant's spread.

The agency noted AY.4.2 "appears to have a modestly increased growth rate compared to Delta" and "accounts for a slowly increasing proportion of cases in the U.K."

The agency is currently monitoring whether the variant has any effect on deaths, hospitalization and vaccine effectiveness and will report its findings when they are available.

Meanwhile AY.4.2 has been detected in a total of 39 countries around the world, according to Outbreak.Info, including Canada, Australia, Japan, and much of Europe. Romania has the highest proportion of AY.4.2 cases behind the U.K.

Despite the spread in the rest of the world, the World Health Organization (WHO) does not appear to have listed AY.4.2 as a separate variant under monitoring, a variant of interest or a variant of concern as of yet. Instead, it lists Delta as a variant of concern, which includes AY.4.2 and all other Delta sub-variants.

The WHO also did not appear to mention AY.4.2 in its weekly COVID epidemiological update on October 19.

In the U.S., Centers for Disease Control and Prevention (CDC) director Rochelle Walensky acknowledged AY.4.2's presence in the country in a press briefing last week. She added: "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 up."

AY.4.2 is characterized by two mutations known as Y145H and A222V. Scientists are still trying to work out exactly what these mutations do and what sort of advantages, if any, they might provide to the Delta variant.

It has already been noted that AY.4.2 appears to be slightly more transmissible than other Delta variants.

A stock photo shows a scientist working with test tubes labelled "COVID-19" in a lab. AY.4.2 sequences have been detected in dozens of countries. mbz-photodesign/Getty