Dec 28, 2021 - Health

CDC slashes estimate of Omicron case prevalence

A man in a red jacket stands by a truck and gets a nose swab for a COVID test.

Most current COVID-19 infections are from the Omicron variant, despite the data update. Photo: Tayfun Coskun/Anadolu Agency via Getty Images

The Omicron variant of COVID-19 represented a much smaller proportion of cases during the week that ended Dec. 18 than previously estimated, the Centers for Disease Control and Prevention said Tuesday.

The big picture: Even though the Delta variant appeared to be the primary strain for most of December, Omicron still represents a majority of cases right now — 58.6% according to the CDC's latest estimates.

Where it stands: The CDC originally forecast last week that the Omicron strain represented 73% of cases for the week that ended Dec. 18. That has since been revised down to 22.5%.

  • Omicron accounted for 58.6% of cases for the week that ended Dec. 25.

Between the lines: The drastic data change is due to the fact that CDC knew Omicron was spreading quickly, but it ultimately discovered fewer Omicron cases after more data came in.

The bottom line: CDC's initial estimates of Omicron prevalence were way off, but the rising caseloads and new data still suggest this variant is driving the country's current outbreak.

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