The Omicron variant of COVID-19 isn’t quite as widespread as the Centers for Disease Control and Prevention (CDC) previously led people to believe.
The agency reported Dec. 20 that 73% of COVID-19 cases across the United States were Omicron, up from just 0.7% two weeks before. Now, that number has been revised all the way down to 22.5%.
CDC estimates of circulating variants including week of 12/25. Notably week of 12/18 estimate of Omicron revised from ~73% to 22.5% (just a tad different!).
Now saying 58.6% of variants are Omicron nationwide. 1/ pic.twitter.com/duYpLSEXQm
— Jason Gallagher (@JGPharmD) December 28, 2021
The data for the week of Dec. 12 to Dec. 18 was revised when the CDC released new data for the most recent available week, Dec. 19 to Dec. 25. Instead of Omicron becoming dominant between Dec. 12 and Dec. 18, Delta was still dominant at the time, making up 77% of cases.
Now, according to the most recent estimate for the week of Dec. 19 to Dec. 25, Omicron is dominant. It’s still only making up 58.6% of cases, though, not the 73% that was once reported.
The numbers may have been skewed because not all COVID-19 cases in the United States are sequenced to determine which variant they are, meaning the CDC can only estimate based on the cases that are sequenced and submitted to the agency. (RELATED: CDC Shortens Isolation Rules For COVID-Positive Health Care Workers Amid Fear Of Understaffed Hospitals)
Omicron is most prominent right now in Health and Human Services region 2 (New York, New Jersey, Puerto Rico and the Virgin Islands) and region 6 (Arkansas, Louisiana, New Mexico, Texas and Oklahoma). There are two regions where Delta is still the dominant variant: region 1 (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont) and region 7 (Iowa, Kansas Missouri and Nebraska).
The new data suggest Omicron may still have more room to spread than previously believed. While the variant is less severe than prior strains of the virus, it is believed to be far more contagious and can more easily infect vaccinated or naturally immune individuals.