DENVER — Officials with the Colorado Department of Public Health and Environment (CDPHE) said that COVID-19 data continues to decline but remains high during an update on the state's response to the pandemic on Thursday.
State Epidemiologist Dr. Rachel Herlihy said the positivity rate declined about 4% to 22%, and hospitalizations are also declining, with 1,444 patients with COVID-19 occupying beds as of Thursday.
COVID-19 Incident Commander Scott Bookman said hospital bed availability has been stable, with the seven-day average of open acute ICU beds around 680.
He acknowledged that hospitalizations may decline at a slower rate as patients who have put off procedures occupy beds, which will continue to stretch the understaffed health care workforce thin.
Herlihy also said it's believed fewer COVID-19 patients are hospitalized due to their symptoms, as opposed to testing positive while in the hospital.
"While things are moving in the right direction, there is still a lot of COVID-19 moving through our communities," Herlihy said.
BA.2 subvariant identified
CDPHE said one case of the omicron subvariant (BA.2) case was identified in late December through genetic sequencing of clinical samples submitted to the state lab.
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CDPHE said it appears the original omicron variant (BA.1) is being replaced in some countries by BA.2 cases. That suggests it may have an advantage over BA.1, such as increased transmissibility.
The state has only detected one case so far, and Herlihy said she does not believe there is widespread transmission of BA.2 in the state.
Herlihy said the BA.2 variant was more prevalent in counties including India and Singapore and more recently has replaced many BA.1 cases in Denmark while also causing a slight bump in their COVID-19 metrics.
>> Video below: Omicron stealth variant harder to detect
She said that's a sign widespread circulation could lead to a slight bump in transmission in Colorado, but it would not be as significant as a new variant developing.
Models illustrate immunity
CDPHE released an updated statewide modeling report on Wednesday estimating 80% of the state's population will be immune to omicron by mid-February.
On Thursday, state health leaders said currently, about 75% of the state's population is immune to omicron infection, and about one in 19 Coloradans are currently infectious.
"All evidence indicates infection prevalence has been at unprecedented levels in January 2022, but the model projects this prevalence will decline in coming weeks, potentially to below 1% by the end of February," CDPHE said in the release.
Dr. Bailey Fosdick is part of Colorado's COVID modeling team, and also an associate professor of statistics at Colorado State University.
To come up with this latest model, she said researchers looked at natural and vaccine-acquired immunity.
"We were really looking at, for every individual, what is their cumulative immunity: due to vaccination history, are they boosted, are they not, did they have one or two shots, how long ago was that? As well as infection history," she said.
The models reflect predictions made with data available now, which, Fosdick said, means they should be considered a short-term prediction, not a long-term one.
"As of right now we're feeling really good about possibly the end of February, [but with] the caveat that a new variant doesn’t pop up between now and then," she said.
"But going forward into late spring-summer, it's really uncertain about what that’s going to look like," she said.
"We can all agree there will be another variant," said Dr. James Neid, Director of Infection Prevention at the Medical Center of Aurora.
"To predict its genetic changes – that’s very difficult," he said. "What that does to the virus and how it infects people, also very hard to predict."
Neid said even though omicron is more transmissible, vaccinations and boosters are working to prevent most people from developing serious illness or dying from the virus. "Good news," he said, would be a continued trend of hospitalizations decreasing.
"Trends today are slightly encouraging," he said. "I hope it continues."
Another caveat to the modeling data is the so-far limited information around omicron reinfection rates. When asked Thursday if someone who recovered from omicron infection was at risk of reinfection, Colorado State Epidemiologist Dr. Herlihy said -- maybe.
"That’s a great question, and a question we are asking right now. We don’t have great data about omicron reinfection," she said.
"That’s obviously something we'd like to learn much more about," she said. "We know, probably short term, there's good protection, but what we don't understand as you get further and further out, what your level of protection, level of immunity, might be from a prior infection."
As COVID changes, so do the state models. Fosdick said how we use this data is changing, too.
"Our discussion is no longer, 'Are we going to run out of hospital beds?' But the conversation we're having [now] is about students missing classes, staff unable to show up to work," she said.
"We've turned from hospitalizations to number of people infected, which has a different feel to it, but also has a different set of ramifications that I think we're all trying to understand," she said.
Bookman said more than 2.5 million medical-grade masks have been given to distributors across the state in the first week of the new state program.
At least 400 locations are currently opted in to distribute KN95 and surgical-grade masks around Colorado.
That includes 164 libraries, 97 fire departments and 148 other community locations.
"Fully vaccinated" definition examined
The CDC published studies highlighting the importance of getting a third booster dose to increase protection against the omicron variant.
Bookman said the state is examining the definition of "fully vaccinated," which is currently considered two doses of an mRNA vaccine, or one dose of the Johnson & Johnson vaccine.
He acknowledged that the definition of "fully vaccinated" could be changed to mean an individual has received all the shots they are eligible for.
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