The Centers for Disease Control and Prevention has drastically reduced its estimate of Omicron cases in the US, saying the variant accounted for about 59 percent of COVID-19 infections as of Christmas Day — a massive drop from the 73 percent previously reported.
The CDC also significantly lowered its estimate for the week before Christmas, saying that the variant accounted for just 22.5 percent of all infections as of Dec. 18. The public health agency previously estimated that Omicron accounted for 73.2 percent of cases that week.
This could mean that the Delta strain could actually be behind many of the current COVID-19 hospitalizations, former FDA chief Scott Gottlieb said.
“Setting aside the question of how the initial estimate was so inaccurate, if CDC’s new estimate of #Omicron prevalence is precise then it suggests that a good portion of the current hospitalizations we’re seeing from Covid may still be driven by Delta infections,” Gottlieb wrote on Twitter.
The CDC blamed the disparity on the rate with which the highly transmissible variant spreads.
“There was a wide predictive interval posted in last week’s chart, in part because of the speed at which Omicron was increasing,” CDC rep Jasmine Reed told Politico. “We had more data come in from that timeframe and there was a reduced proportion of Omicron.”
The revised Christmas model includes a narrower confidence range of Omicron’s prevalence: 41.5 to 74 percent. The new model suggests that Delta still accounts for 41.1 percent of infections across the country.
Tuesday’s revision came as the US logged its highest single-day total of new COVID-19 cases — with 441,278 infections passing the previous daily record by nearly 150,000 cases, according to the report.
Reed also said the daily case total is likely an “overestimate” due to lagging state reporting. Many testing centers were closed over the holiday weekend.
“The counts of cases will become more stable after the new year,” she told Politico.
Meanwhile, former US Surgeon General Jerome Adams criticized the CDC for its decision to cut isolation periods from 10 days to five.
“I love the CDC. Grew up wanting to work there and have been one of their most ardent defenders. I never dreamed the day would come when I would advise people NOT to follow their guidance,” he said in a tweet.
“They wouldn’t even follow it for their own family,” he added.