https://www.siliconvalley.com/2022/03/22/covid-what-other-countries-can-tell-us-about-the-impact-of-ba-2/ > (CNN) — After weeks in free fall, new Covid-19 cases are starting to level off in the US, as the BA.2 subvariant continues its ascent. > BA.2 caused about 35% of cases in the US last week, up from 22% the week before, according to new estimates from the United States Centers for Disease Control and Prevention, which were posted on Tuesday.