Cases of Potentially Faster-Spreading AY.4.2 Variant Hit 40,000, up 10,000 in a Week

At least 40,000 cases of the Delta AY.4.2 COVID variant have now been detected worldwide, according to sequencing data.

AY.4.2 is a sub-lineage of the Delta variant that appears to have mutated a growth advantage compared to other Delta versions.

However, AY.4.2 also does not appear to be any more vaccine-resistant than Delta and has failed to gain much of a foothold in the U.S., current data shows.

The variant is found almost entirely in the U.K., where it has accounted for around 15 percent of samples sequenced per day recently.

The total number of AY.4.2 sequences found worldwide was 40,215 according to variant tracking tool Outbreak.info as of November 14, of which 37,883 were in the U.K.

The latest worldwide figure marks a rise of nearly 10,000 cases in a week.

Two mutations notably associated with AY.4.2 are called Y145H and A222V, both of which affect the spike protein that the SARS-CoV-2 virus uses to enter human cells. Scientists have previously told Newsweek that not a lot is known about the two mutations.

The U.K. government has acknowledged that the AY.4.2 has a small growth advantage over other Delta variants and has designated the variant a VUI, or variant under investigation.

At the same time, a government study suggested that the variant does not seem to have mutated any further resistance to vaccines than Delta already had.

Including the U.K. and the U.S., AY.4.2 has been detected in a total of 39 countries worldwide, with Romania and Poland recording some notable prevalence, Outbreak.Info shows.

Most countries have very few cases, including the U.S. which had only reported 25 sequences from 13 states as of November 14.

It is not unusual for a virus to mutate. They do so all the time as they spread from person to person.

These changes are random, and most of them are inconsequential or actually detrimental to the virus, meaning they fizzle out, experts have previously told Newsweek.

But occasionally a mutation may provide the virus with some sort of advantage that allows it to outperform other types and spread.

Where variants first emerge also makes a difference. Factors include local vaccine rates, population density, and existing immune response rates.

The Delta variant and all of its sub-lineages currently account for 99.9 percent of all COVID cases in the U.S., according to Centers for Disease Control and Prevention (CDC) data.

Coronavirus laboratory
Two laboratory staff members in full PPE working on COVID sequencing at the Pasteur Institute in Paris on January 21, 2021. The spread of AY.4.2 can be tracked with sequencing data. Christophe Archambault/AFP / Getty