A COVID-19 Delta subvariant—which potentially spreads faster—has been spotted at labs in at least eight states and 42 countries.

Named AY.4.2 and sometimes called “Delta Plus,” the strain has led to an investigation by health authorities in the United Kingdom and has been recognized in labs in California, Florida, Maryland, Massachusetts, Nevada, North Carolina, Rhode Island, Washington, and the District of Columbia, according to CBS News.

So far, while it may spread faster, nothing points to more severe illness and vaccines should remain effective, according to health authorities. The subvariant raises Delta by an additional three mutations, impacting “spike proteins that studs the surface of the virus,” according to Forbes. AY.4.2 only has taken up a small fraction of U.S. cases, but officials are working to study the latest Delta variant.“We have teams that are constantly reviewing the genetic sequence data and looking for blips, an increase in a certain proportion or just something that’s completely new,” says executive secretary of the U.S. government’s SARS-CoV-2 Interagency Group, Dr. Summer Galloway.