Around the world, the latest Omicron subvariant, BA.5, is quickly becoming the dominant strain of the SARS-CoV-2 virus. It just took the top spot in the U.S.: As of the last week of June, BA.5 made up more than half of all new COVID-19 cases, according to new estimates from the U.S. Centers for Disease Control and Prevention (CDC). That’s up 10 percentage points compared to the prior week.