Dominant COVID-19 Strain BA.2 , Not Showing Signs of Causing Surge in US.br CNN reports that BA.2, the now dominant strain of coronavirus in the United States, is living up to its designation as the "stealth variant.".br A subvariant of Omicron, BA.2 is br responsible for 3 out of 4 positive br COVID-19 cases in the United States.br Still, experts say there is no indication br yet that the subvariant could cause br another surge in infections.br As BA.2 dominates other coronavirus br strains, the overall number of cases in the br country has decreased.br This is a clear example of how these two trends are not necessarily tied together. , Jessica Justman, an epidemiologist at Columbia University's br Mailman School of Public Health, via CNN.br Health experts say it's unclear why the br United States hasn't experienced the br same increase in new infections as Europe.br One theory revolves around estimates that 95 br of Americans have differing levels of immunity.br Per the CDC, nearly br 45 of Americans currently have infection-related antibodies.br But such high levels of immunity br have come at a steep cost.br According to data from Johns Hopkins University, over 980,000 Americans br have died due to COVID-19.