Health Security Agency on October 20 designated AY.4.2 as a Variant Under Investigation, a step below Variant Of Concern. Preliminary evidence suggests that AY.4.2 spreads between 12 and 15 percent more frequently among household members compared with other Delta viruses.Īlarmed by AY.4.2’s rapid rise, the U.K. Of more concern is that it's steadily outcompeting other members of the Delta family. Although the original Delta variant remains the most dominant in the U.K., this new mutant now accounts for more than 12 percent of infections, up from less than 4 percent in early September.
The continuing spread of Delta has led to a newer subtype, called AY.4.2, which carries two additional mutations. While the summer surge of COVID-19 wanes in the United States, a more transmissible version of the Delta variant has been spreading in the United Kingdom since July.
