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BA.4, BA.5 gain ground in US, pose higher risk of breakthrough infections
news.movim.eu / ArsTechnica · Monday, 6 June, 2022 - 22:17
Omicron subvariant BA.2.12.1 has overtaken BA.2 as the dominant version of the pandemic coronavirus in the US, now accounting for an estimated 59 percent of cases nationwide . But BA.2.12.1's reign may end as quickly as it began, with yet another batch of omicron subvariants gaining ground—BA.4 and BA.5—and threatening to cause more breakthrough infections.
BA.2.12.1 has a transmission advantage over BA.2, which itself has an edge over the initial omicron subvariant, BA.1, that caused a towering surge of US cases in mid-January. BA.2 peaked in mid-April, accounting for 76 percent of US cases at its height. But then came BA.2.12.1 , which is named for being the 12th lineage stemming from BA.2 and the first branch of that BA.2.12 lineage.
When BA.2 peaked in mid-April, BA.2.12.1 accounted for about 18 percent of cases. It reached about 43 percent prevalence by mid-May and has since overtaken BA.2, which currently accounts for only about 35 percent of cases. BA.2.12.1 is dominant in every region of the country, except for the Northwest, according to the Centers for Disease Control and Prevention.