The proportion of COVID-19 cases involving the omicron subvariant BA.2 has declined for the second consecutive week as a new omicron sublineage appears to be gaining a foothold in the U.S., CDC data shows.
The sublineage — BA.2.12.1 — accounted for 28.7 percent of new COVID-19 cases in the week ending April 23, according to the CDC's latest variant proportion estimates. This figure is up from 19.4 percent in the week ending April 16 and 13.7 percent in the week ending April 9.
While BA.2 is still the nation's dominant strain, its prevalence has fallen from 74.9 percent on April 9 to 68.1 percent as of April 23.
BA.2.12.1 is estimated to have a 27 percent growth advantage over BA.2, which is already more transmissible than the original omicron strain. The sublineage and a closely related strain called BA.2.12 are widely circulating in New York and likely contributing to an uptick in cases, health officials said April 13.
Nationwide, COVID-19 cases have increased 53 percent over the past 14 days as of April 25, according to HHS data tracked by The New York Times.