CDC slashes estimate on spread of Omicron, but warns variant is now dominant

Data shows Delta variant still prevalent as Omicron hits US shores

People get tested for Covid-19 at a testing site in Washington, DC (AFP via Getty Images)

The Centers for Disease Control on Tuesday moved to revise its model estimating the spread of different variants of Covid-19 in the US to significantly reduce the share of infections caused by Omicron.

Previous charts on the CDC’s website showed over the weekend that the Omicron variant was estimated to be responsible for roughly 73 per cent of cases across the US in the data from 18 December. Those estimates changed on Tuesday, when CDC officials updated the graph and cut that number significantly. The new chart estimates Omicron as responsible for just 22.5 per cent of cases across the US on 18 December, while the preceding Delta variant was credited with causing roughly 77 per cent of US infections.

That means it took roughly one more week than previously thought for the Omicron variant to become the dominant strain of Covid-19 in the US, according to CDC figures. The same chart estimates that Omicron was responsible for 58.6 per cent of infections on data posted Christmas Day.

A spokesperson for the agency confirmed to Politico that the data was changed, and explained that the agency had overestimated the speed at which Omicron was spreading in the US, revising the data when solid figures became available.

“There was a wide predictive interval posted in last week’s chart, in part because of the speed at which Omicron was increasing,” CDC spokesperson Jasmine Reed said in a statement, adding: “We had more data come in from that timeframe and there was a reduced proportion of Omicron.”

The spread of Omicron is being credited by health experts as contributing to a surge of new cases across the US, including among some vaccinated individuals. Public health officials have stressed that the likelihood of contracting the disease or experiencing severe symptoms remains much lower for vaccinated persons.

The US’s response to the pandemic has once again come under scrutiny and criticism as the new variant spreads due to an apparent shortage of tests and the experience many Americans have had encountering long lines at Covid-19 testing sites.

Officials in the Biden administration have scrambled to respond to the issue; Vice President Kamala Harris admitted in an interview that the administration didn’t see Omicron coming, while White House press secretary Jen Psaki was pilloried for a snarky response to a reporter who asked if the federal government would consider mailing at-home Covid tests to Americans.

President Joe Biden addressed the evolving situation in an address last week before the Christmas holiday, explaining that his administration would not push to reinstate restrictions on businesses and public life and instead portrayed getting vaccinated (fully) against Covid-19 as an “obligation” and civic duty of every American.

“You have an obligation to yourselves, to your family and frankly, I know I’ll get criticised for this, to your country,” he said last Tuesday. “Get vaccinated now. It's free, it's convenient. I promise you it saves lives. And I honest to God believe it’s your patriotic duty.”