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.
It’s unclear exactly what’s ahead in this latest phase of the pandemic. What we know of the two subvariants so far is mixed.