Yeah, this was brought up in this thread a few weeks ago:
This new Omicron variant is so transmissible. My sister's immediate family has some of her grandkids and parents testing positive even though they were as vaccinated as they could be. A tough way to spend the Holidays. :( :( :(
forums.audioholics.com
I found some articles discussing the CDC's revisions (It's still unclear to me what the prevalence of "Ice Ice Baby" is, however).
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Why the CDC lowered its estimate
The CDC uses a model called Nowcast to estimate coronavirus variants’ prevalence in the United States. It can take two to three weeks after a specimen is collected to determine its genetic sequence, according to the CDC — meaning officials don’t immediately know what variant of the coronavirus a person is infected with when they test positive for COVID-19. Additionally, genetic sequencing isn’t performed on all coronavirus samples.
Nowcast uses genomic surveillance data from previous weeks to provide a more recent estimate on a variant’s spread, the CDC says. Those estimates, however, can change as the CDC gets more data.
The estimates also use confidence intervals, or a range of possible values, The New York Times reported. Jasmine Reed, a CDC spokesperson, told Politico that the change in the agency’s estimate was due to the rate at which the omicron variant is spreading. “There was a wide predictive interval posted in last week’s chart, in part because of the speed at which omicron was increasing,” Reed said, according to Politico. “We had more data come in from that time frame and there was a reduced proportion of omicron.” But a CDC spokesperson told Reuters “it’s important to note” that the agency is “still seeing a steady increase in the proportion of omicron” cases. Experts told The New York Times it’s likely the CDC’s current estimate on omicron’s prevalence will change, too.
“I just want people to be very aware that that is an estimate, that’s not actually from sequence-confirmed cases,” Nathan Grubaugh, an epidemiologist at the Yale School of Public Health, told the NYT. “With omicron in particular, it’s been very difficult to have any sort of projections, because things are changing just so so rapidly.”
Experts weigh in on the revision
David O’Connor, a virologist at the University of Wisconsin-Madison, told The New York Times that the CDC’s original estimate on omicron’s prevalence during the week of Dec. 18 “seemed high” and noted that the number was based on a “relatively small number of sequences.” “It’s like playing ‘Name That Tune,’ and trying to say, based on just the first note, if the song is ’Ice Ice Baby’ by Vanilla Ice, or ‘Under Pressure,’” O’Connor told the outlet. “Without more data, it can be really hard to know which one it’s going to be.”<<<