A potentially faster-spreading "sub-lineage" of the coronavirus Delta variant named AY.4.2 has been spotted by labs in at least 8 states, and health authorities in the United Kingdom say they are investigating a growing share of cases from this strain of the virus.
Labs in California, Florida, Maryland, Massachusetts, Nevada, North Carolina, Rhode Island and Washington state, plus the District of Columbia, have so far spotted at least one case of AY.4.2.
While it may spread somewhat faster, health authorities have not found evidence of more severe illness caused by the variant, and they say current vaccines remain effective against it. The sub-lineage has remained a small fraction of circulating cases in the U.S. for several weeks, but American health officials say they are already ramping up efforts to study the new Delta variant descendant.