As much as 80% of Coloradans may be immune to the dominant omicron variant by mid-February, new pandemic modeling indicates, helping to shepherd in a period of pandemic calm that could last into the summer.

Colorado researchers estimate that the omicron wave, which began around the Christmas holiday and is believed to have peaked two weeks ago, will continue to subside in the coming weeks. They project that roughly 5% of all residents are now infected with omicron, the more infectious but less severe form of the virus that causes COVID-19. Nearly half of the state has likely been infected with omicron, the researchers wrote in a report published this week, and 65% of Coloradans will have been infected by the end of next month.

State officials said last week as much as 10% of the state’s population may have been infected simultaneously during omicron’s peak.

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The report bolsters what state officials and data have been indicating for the latter half of January: Omicron’s wildfire-like emergence and spread infected an unprecedented number of Coloradans at unprecedented speeds. But that rapid rise means the peak came sooner and the downturn began quicker. It also may mean that enough people are immune that the coming months may be relatively quiet, a welcome reprieve after a months-long delta surge, which was followed closely in December by omicron. The outstanding question, though, is if yet another variant emerges somewhere between now and then and has the same disruptive potential.

Speaking to reporters Thursday, state epidemiologist Rachel Herlihy said a new variant “would certainly change the story” of the next few months. But vaccinations and immunity gained from prior infections “leaves us in a very different place than we have been during the pandemic.”

Hospitalizations, which surged again during omicron, have been falling steadily; though they cautioned that unknowns remain, the researchers said that trend should continue into next month. 

As of Wednesday afternoon, 1,526 Coloradans were hospitalized with COVID-19. That’s down from a recent high of 1,676 set last week. Gov. Jared Polis said last week that roughly two-thirds of those patients were hospitalized because of the disease, while the remaining third were in the hospital for another reason but subsequently tested positive for COVID-19. Officials have said such “incidental cases” still place a strain on patients and the health care system because they take up additional resources and could exacerbate the patient’s other condition.

But in their latest report, the researchers projected that COVID-19 hospitalizations will dip to “well below 500” by the end of February. There have not been fewer than 500 Coloradans hospitalized with the virus since the second week of August. 

Though rates of infection and hospitalizations still remain high statewide and have yet to begin to decline in some areas, Herlihy and Scott Bookman, the state’s COVID-19 incident commander, both expressed “cautious optimism” about the trajectory of the trends Thursday.

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The breadth of infection brought on by omicron is “unprecedented,” the researchers wrote. It remains high: The prevalence of the virus — even two weeks after the wave peak — is at 5%; previous waves peaked at 2% of the state currently infected. 

“We estimate that Omicron has infected roughly 42% of the Colorado population to date,” the researchers wrote. “By late-February, we estimate that this will increase to 65%. This increase of 23% means that a large number of Coloradans may be infected with Omicron in the weeks ahead.”

Still, the prognosis is good: “Our model and others project a relatively steep decline across the month of February.”

Omicron’s arrival came right on the heels of delta’s ebbing. Immunity acquired from vaccinations earlier in 2021 and from infections before the delta wave had both declined by this past fall, the researchers wrote. But omicron’s ubiquitous presence has rocketed up immunity and will continue do so: The team estimated that roughly 75% of Colorado is immune to the variant, which is the overwhelmingly dominant strain of the virus present here now, and that roughly 80% will be immune in the coming weeks.

Jon Samet, the dean of the Colorado School of Public Health and a member of the modeling team, told The Denver Gazette earlier this month that the next few months should be calmer, unless a new variant with the disruptive potential of omicron emerges.

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Should that not happen, though, the researchers wrote that the state should have a window “to prepare for the possibility of yet another COVID-19 wave driven by a variant.” That preparation, they continued, should include continued distribution of high-quality masks, as well as continued emphasis on vaccinations and boosters.

There will likely be isolated outbreaks during that period, they project, particularly among the roughly 29% of the population that is not fully vaccinated (nearly 80% is at least partially vaccinated).

“This picture of a high rate of population immunity has led to suggestions that the COVID-19 pandemic could be ending and that an era is beginning in which COVID-19 is endemic, causing outbreaks but not society-disrupting epidemic waves,” the researchers said. “… We agree that a lull lies ahead with the Omicron variant in Colorado but are quite uncertain as to how long it will last.”