Nearly 38% of Coloradans are estimated to have been infected with the novel coronavirus through January, a Centers for Disease Control and Prevention study found, putting the Centennial State ahead of much of the rest of the nation.

Only eight states, plus Puerto Rico, are estimated to have had fewer residents infected with the virus, according to CDC data. The projections indicate 2.09 million Coloradans have been infected, and roughly 10% of those cases came during the first month of the omicron wave that began in mid-December.

A year ago, the CDC estimated that nearly 686,000 Coloradans had been infected. The 12 months that followed would see the wide availability of vaccine but also the emergence of two infectious variants that drove up case rates for the latter half of 2021.

The CDC’s study, which it updates regularly, relies on results from “residual serum” from other, non-COVID-19 tests. That residue, collected from two private labs, is tested for antibodies for the virus. The results do not include people who have been vaccinated against the virus.

The study’s updated results come as Colorado – and much of the United States – emerges from the omicron wave and enters into what experts hope will be a quiet spring for a pandemic entering its third year. Cases here have dropped significantly since the omicron wave peaked in mid-January: The state has reported fewer cases on average over the past seven days than it has at any point since July. Hospitalizations have plunged by roughly 1,300 in six weeks; there have not been this few Coloradans hospitalized with COVID-19 since the first week of August.

The CDC’s projections reflect several hundred thousand more infections than what’s reported by the state Department of Public Health and Environment. As of Thursday afternoon, the state reports that just over 1.3 million cases have been reported here, some of which are re-infections. 

Overall, the CDC estimates that 43.3% of the United States has contracted the virus, putting Colorado more than 5 percentage points ahead of the national average and well into the top 10. The state similarly has had one of the lowest death rates in the nation, though more than 12,500 Coloradans have died due to COVID-19 since the pandemic began almost exactly two years ago.

“We applaud Coloradans who have gone above and beyond in the past two years to slow disease transmission by getting vaccinated and staying up to date on all recommended COVID-19 vaccinations, staying home when sick and following other public health guidance like wearing masks and avoiding large crowds,” a spokeswoman for the state health department said in an email this week. “With their commitment, according to the CDC, compared to other states, Colorado ranks 10th lowest for deaths per 100,000 over the course of the pandemic.”

Jon Samet, the dean of the Colorado School of Public Health, said Colorado has done better than average. Though the state has had moments where it was among the worst in the nation for case rates, “everybody shared that status across time.”

He attributed Colorado’s success – relative to other parts of the nation – to two things.

“One is we’ve had some parts of the state that constitute large proportions of the population that have been quite adherent with vaccination and non-pharmaceutical interventions,” Samet said, referring to things like masking and social distancing. “And I think the state and counties have been willing – for the most part – to implement measures as they’ve been needed. So I think it’s a combination of doing what public health needed to do, and also people in our state – for the most part, certainly not all and it’s (patchy) – but being adherent enough to the recommendations in public health orders.”

Nearly 73% of Coloradans over the age of 4 are fully vaccinated, according to state data, and 81.3% have been inoculated with at least one dose. Samet and a team of experts estimated last month that 90% of Colorado is likely immune to omicron, thanks to infection and vaccination.