Delta Variant Subtype on Rise in United Kingdom

FRIDAY, Oct. 22, 2021 (HealthDay News) -- A subtype of the delta variant of the coronavirus is causing a growing number of infections in the United Kingdom and is being closely monitored there and in other countries.

During the week of Sept. 27, the AY.4.2 variant accounted for about 6 percent of cases in the United Kingdom and is "on an increasing trajectory," according to the U.K. Health Security Agency, CNN reported. Despite its spread in the United Kingdom, officials there have not yet classified it as a variant of concern. While some experts have suggested that AY.4.2 may be somewhat more transmissible than the original delta variant, that has yet to be confirmed.

"As AY.4.2 is still at fairly low frequency, a 10 percent increase in its transmissibility could have caused only a small number of additional cases. As such, it hasn't been driving the recent increase in case numbers in the U.K.," expert Francois Balloux, director at the University College London Genetics Institute, told the Science Media Center earlier this week, CNN reported.

A small number of AY.4.2 cases have also been reported in Denmark and the United States. While new variants have repeatedly competed to become the dominant strain globally in the past year, experts say it is too soon to know whether AY.4.2 will become significant.

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