Omicron coronavirus subvariants BA.4 and BA.5 are now accounting for an estimated 35 percent of US cases, according to the Centers for Disease Control and Prevention. The subvariants are on a course to reach dominance at a faster clip than the subvariants before them, including the current reigning subvariant, BA.2.12.1, which is now in decline.
The pair—which share the same mutations in their SARS-CoV-2 spike proteins but have differences elsewhere in their genomes—are expected to reach dominance "in a few weeks," Dr. Shishi Luo tells Ars. Luo is the head of infectious diseases at Helix, a California-based population genomics and viral surveillance company that works with the CDC to help track emerging coronavirus variants nationwide.