1 in 99 people in Colorado estimated to be infectious with COVID-19

By: - September 20, 2021 12:20 pm
UCHealth vaccine trial

UCHealth registered nurse and research coordinator Stacie Kenny administers a shot to the first participant in UCHealth’s COVID-19 vaccine study, conducted in northern Colorado. Participants in the study receive either a placebo vaccine or a vaccine developed by Oxford University and pharmaceutical company AstraZeneca. (Courtesy UCHealth)

Colorado is currently in its fifth wave of the coronavirus pandemic, with 1 in 99 people in the state estimated to be infectious with COVID-19, according to a statewide modeling report released by the Colorado Department of Public Health and Environment and the Colorado School of Public Health.

The report estimates 70% of the Colorado population to be immune to COVID-19 either from a previous infection or from being vaccinated against COVID-19, though an increase of COVID hospitalizations and deaths is predicted.


If community spread of COVID-19 stays on the current trajectory, the model predicts that hospitalizations and deaths will increase through September, and hospital demand will increase through mid-October, according to the report. 

The estimated effective reproductive number is 1.1 in Colorado as of Sept. 14, which indicates an increasing number of infections. However, this value is lower than it has been over the last month, according to a Sept. 17 press release from the CDPHE and the Colorado School of Public Health. An effective reproduction number below 1 means the number of infections is decreasing, whereas an effective reproduction number above 1 means the number of infections is increasing. 

Rachel Herlihy, state epidemiologist for Colorado, participates in a news briefing on the state’s response to COVID-19 on Nov. 24, 2020. (Governor Jared Polis Facebook)

“The state data and the modeling indicates we are not quite out of the woods yet. In the short-term, transmission control measures, like masking and social distancing, will continue to reduce peak hospital demand,” state epidemiologist Rachel Herlihy said in the press release. “Longer term, an increase in vaccination rates will continue to be crucial to reducing hospital demand and saving lives.”

Symptomatic infection of the delta variant is 1.7 times more likely to lead to hospitalization of a person infected with it than with the alpha variant, according to the report. The report drew information from a study in the United Kingdom and Canada. 

The projections in the model are based on COVID-19 hospital data through Sept. 13 and COVID-19 vaccine data through Sept. 12. 

All Colorado state employees must either be fully vaccinated by Sept. 20 or participate in testing two times a week. Additionally, all federal employees  must be fully vaccinated, as a result of President Joe Biden’s Sept. 9 executive order

Colorado has hundreds of vaccine locations throughout the state, according to the CDPHE website. Colorado is hosting large community vaccine sites at the Aurora Municipal Center in Aurora, the Southwest Plaza Mall in Littleton, the Chapel Hills Mall in Colorado Springs, and Dick’s Sporting Goods Park in Commerce City.

The report was prepared by the Colorado COVID-19 Modeling Group, which includes Elizabeth Carlton, Debashis Ghosh, Irina Kasarskis, Talia Quandelacy, and Jonathan Samet of the Colorado School of Public Health, Sabina Altus and David Bortz of the University of Colorado Boulder Department of Applied Mathematics, Jude Bayham of Colorado State University, Andrea Buchwald of the University of Maryland School of Medicine, and Parker Jackson and David Jacobson of Vanadata. 


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