The United States appears to be in the midst of another biological baton pass between Covid-19 variants. The Omicron lineage BA.2 and its spinoff, BA.2.12.1, drove cases this spring, building into waves of infections in places like the Northeast and parts of California. Now, two other forms of Omicron, BA.4 and BA.5, are eating into the BA.2 group’s dominance.
More than 1 in 5 Covid-19 infections last week were caused by BA.4 and BA.5, according to updated estimates posted [June 14] by the Centers for Disease Control and Prevention. That’s up from 13% the week prior. The rest of the cases are from the BA.2 lineages.
BA.4 and BA.5 are picking up speed because they’re able to evade the body’s antibody response even more so than other variants.
Already, transmission has been picking up in areas including parts of Florida and New Mexico. The South experienced devastating infection waves the past two summers, likely in part because people headed indoors to escape the heat, and experts are watching to see if the region again sees a summertime surge.
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According to the latest CDC data, the region with the highest prevalence of BA.4 and BA.5 at this point — at more than 30% — is the one including Texas, New Mexico, Arkansas, Oklahoma, and Louisiana.
