In its evolutionary fight for survival, the COVID virus is switching strategies: It’s becoming a master at slipping past our immune systems. And that, say experts, is largely why we’re dealing with an unexpected surge.
Powered by two mutations, new lineages of the omicron variant — called BA.2 and its more recent descendants BA.2.12.1, BA.4 and BA.5 — are increasing rates of vaccine breakthrough and reinfection, according to an analysis published Saturday by Trevor Bedford, a virologist at the Fred Hutchinson Cancer Research Center in Seattle, who studies the evolution of viruses.
These latest strains are succeeding “not because they’re more contagious, as much as they are more immune evasive,” Dr. Paul Offit, an FDA adviser and director of the Vaccine Education Center at Children’s Hospital of Philadelphia, said at a recent presentation at UC San Francisco. “This is something that surprises virologists.”