COVID antigen testers at UW-Eau Claire Monday in Eau Claire, WI. The test is for those who are asymptomatic and takes about 20 minutes from the time the swab is taken until the results come back. (Photo by David Joles/Star Tribune via Getty Images)
By Paul Best | Fox News
The United States set a record for new COVID-19 cases at 441,278 on Monday.
The CDC significantly reduced its estimate for how prevalent the omicron variant of COVID-19 is in the United States on Tuesday, saying that the new variant was only responsible for 22.5% of new cases in the week that ended Dec. 18, not the alarming 73.2% that it had originally estimated last week.
For the week ending Dec. 25, the agency says omicron accounted for 58.6% of all new cases.
Jasmine Reed, a spokesperson for the CDC, noted that there was “a wide predictive interval posted in last week’s chart,” and the downward revision was partly due to the “speed at which Omicron was increasing.”
“CDC’s models have a range, and… we’re still seeing steady increase in the proportion of Omicron,” Reed told Fox News Digital. “In some regions in the country, Omicron accounts for ~ 90% or more of cases.”
Dr. Jerome Adams, the former surgeon general in the Trump Administration, explained that the revision was likely partly due to a responder bias caused by a testing quirk with omicron called “S gene dropout,” in which one of the three target genes is not detected. When that gene is not detected, it can be an immediate marker for omicron.
“A lot of people were seeing this S dropout on the tests even before they got the follow-up genetic testing, and so those samples were disproportionately more likely to be sent in for sequencing,” Dr. Adams told Fox News Digital.
As the CDC collects more data, they can more accurately pinpoint the proportions of each variant throughout the country, according to Dr. Li Tang, an associate faculty member in the Department of Biostatistics at St. Jude Children’s Research Hospital.
“Earlier, they probably relied on a small number of available sequences. It should be also noted, although the confidence interval now is narrower, the range is still big, covering from 41.5% to 74%, suggesting large uncertainty,” Dr. Tang told Fox News Digital.