BA.2.12.1 poised to become dominant in US, raising concern for future vaccines

Enlarge / A medical worker arranges nucleic acid samples at a makeshift nucleic acid testing site on May 3, 2022 in Beijing, China. (credit: Getty | Pang Songgang)

The omicron subvariant BA.2.12.1 is poised to become dominant in the US, currently accounting for an estimated 36.5 percent of all US SARS-CoV-2 cases, according to the latest estimates released Tuesday by the Centers for Disease Control and Prevention.

The subvariant's ascent is the latest rapid succession of omicron subvariants, from the sky-scraping peak of cases from the initial omicron subvariant BA.1 in January, to the current bump driven by the subvariant BA.2, which achieved dominance in March. As before, the reason for the viral usurping is that omicron subvariants continue to evolve advantages: BA.2.12.1 has a transmission advantage over BA.2, which had a transmission advantage over BA.1, which had a significant advantage over delta.

The imminent reign of BA.2.12.1 raises concern for yet another wave of infections and poses questions about how effective future omicron-specific vaccines could be against symptomatic infections.