Estimates released by the Centers for Disease Control and Prevention today indicate that the share of cases tied to Omicron variants BA.4 and BA.5 increased 79% in the past week. That means, even as the more transmissible BA.2.12.1 Omicron subvariant became officially dominant in the U.S. last week, it’s already being pushed out by newcomers
BA.4
On November 9, 2021, the first case of a new Covid variant was detected in South Africa. On November 26, with cases rising across that country, the World Health Organization declared it a “variant of concern,” noting a likely increased transmissibility. They called it Omicron. By December 1, the first cases were found in the