Nearly all new U.S. Covid-19 cases last week were linked to the omicron coronavirus variant, the Centers for Disease Control and Prevention reported Tuesday, as the highly transmissible new strain has quickly overtaken the delta variant and sparked new surges nationwide.
The omicron variant, also known as B.1.1.529, was detected in approximately 95.4% of all new cases for the week of December 26 – January 1, the CDC estimates, while 4.6% were linked to the delta variant.
That’s up from the omicron variant making up 77% of cases last week, 37.9% the week ending December 18 and just 8% the week ending December 11.
The variant makes up the majority of cases in every U.S. region, with the regions with the highest percentage of omicron cases including New York and New Jersey, Texas and its surrounding states and the Southeast.
The region that includes Iowa, Kansas, Missouri and Nebraska has the lowest share of omicron cases, with an estimated 77.4% of new cases last week linked to the variant.
239%. That’s the increase in the number of U.S. Covid cases over the past two weeks, according to public health data compiled by the New York Times. The country is recording a seven-day average of 486,658 daily new Covid-19 cases, according to the Times, which is up from approximately 118,000 in mid-December.
The omicron variant has surged throughout the U.S. since the first case was formally detected on December 15, spiking cases in areas like New York City, Washington, D.C., and Florida and spurring new mitigation measures, event cancellations and school closures. The new strain has proved to be more resistant to vaccines when it comes to preventing infections, though evidence suggests the shots are still protective against severe illness and death and booster doses provide added protection. Early studies have suggested the variant may produce milder disease than previous coronavirus strains, potentially due to how the variant appears to be more limited to airways and is less prevalent in the lungs. Hospitalizations are on the rise, however, particularly among the unvaccinated—including children—and the World Health Organization cautioned Tuesday that more studies are needed before reaching conclusions about the variant’s severity.