Viruses constantly change through mutation and sometimes these mutations result in a new variant of the virus. Sometimes new variants emerge and then disappear. Other times, new variants emerge and continue to spread. Scientists have documented multiple variants of the virus that causes COVID-19 around the world. Scientists are studying these variants to learn more and control their spread.
Centers for Disease Control (CDC) and the World Health Organization (WHO) classify some variants as variants of concern. CDC defines a variant of concern as one that may spread more easily, cause more severe disease, reduce the effectiveness of treatments or vaccines, or be harder to detect using current tests.
The CDPHE laboratory and some private laboratories routinely do genetic tests on thousands of COVID-19 samples from around the state each week. This allows CDPHE to track the variants that are circulating in Colorado. Variant data is available on CDPHE’s data dashboard.
On November 26, 2021, WHO identified a new variant of concern and named it “omicron.” Omicron was first detected by scientists in South Africa.
On December 1, 2021, the California and San Francisco Departments of Public Health confirmed that a recent case of COVID-19 in California was caused by omicron variant. The person who tested positive for omicron was a traveler who had recently returned from South Africa.
On December 2, 2021, CDPHE confirmed its first case of omicron variant in Colorado. The case was identified in a Colorado resident who had recently traveled to southern Africa for tourism. This case was identified following a positive test result through routine case investigation. The Colorado State Laboratory conducted genome sequencing on the specimen and confirmed the presence of omicron variant.
CDPHE is watching closely for omicron cases using three main disease monitoring systems: a robust wastewater surveillance program, enhanced case investigation and contact tracing, and traveler monitoring. You can see how many omicron cases have been identified in Colorado on our COVID-19 data dashboard.
There is still a lot to learn about omicron variant. Some mutations on omicron variant may help the variant spread more easily than other variants of the virus. It’s also possible that some treatments may be less effective, increasing the risk of reinfection.
We still are learning about how effective existing vaccines are against omicron. Vaccines are still the safest, most effective way to slow the spread of COVID-19 and its variants, as well as to avoid the worst outcomes (severe illness, hospitalization, and death) among those who do become infected. All Coloradans age 5 and older should protect themselves by getting a COVID-19 vaccine and getting a booster when they’re due for one.
Delta variant was first identified in India in December 2020. Right now, almost all COVID-19 cases in Colorado are caused by delta variant. Data shows that delta spreads more than twice as easily as earlier variants.
The COVID-19 vaccine is effective against delta variant. While some vaccinated people can still become infected with delta and spread it to others, the vaccine works very well to prevent serious illness and hospitalization in people who do get breakthrough infections. Monoclonal antibody therapy also works well to help people infected with delta get better.