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The Weld County Health Department continues to monitor and respond to COVID-19 in our community with the help of several local, state, and federal partners. Find information on the pages below about COVID-19 vaccines, other prevention and preparedness strategies, testing opportunities, and the most current data from our experts.


The virus that causes COVID-19 is constantly changing and adapting. New variants of the virus are expected to occur, as has been the case in the United States and globally throughout the pandemic. A Variant of Concern (VOC) is "a variant for which there is evidence of an increase in transmissibility, more severe disease (for example, increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures."

Currently, there is one VOC in the United States: Omicron. The Omicron variant was first classified as a VOC in the United States on November 30, 2021. In the wake of its emergence, local, state, and federal health officials are closely monitoring its movement and characteristics. More research is needed to know how Omicron affects the risk of severe infection or death and how the vaccines fare against it. Still, all approved COVID-19 vaccines reduce the risk of severe illness, hospitalization, and death from COVID-19. 

Omicron has been confirmed in Colorado, including in Weld County. Omicron became the main variant circulating in Colorado starting the week of December 19, 2021, and has been the dominant variant in the United States, including in the Mountain West region. 

For more information about variants, go to the CDC's "Variants of the Virus" webpage.