Colorado is in its fourth coronavirus wave as more contagious variants become dominant among cases

Colorado has entered its fourth coronavirus wave as more contagious variants of the disease have become the dominant form spreading across the state. 

Hospitalizations are at their highest level since Feb. 19 and cases have risen sharply in recent weeks, though not among Coloradans 50 and older, who have mostly been vaccinated.

“It does appear that we have entered our fourth wave of illness,” Dr. Rachel Herlihy, the state’s epidemiologist, said at a news conference on Friday at the governor’s mansion in downtown Denver. “But this wave is looking a little bit different. We have variants that are making spread of the virus easier, potentially causing more severe cases in some instances. But we also have a segment of the population that is protected through vaccination.”

An estimated 43% to 45% of new cases in Colorado are among the B.1.1.7 strain of coronavirus first identified in the U.K., which is believed to be far more transmissible. Another 18% to 20% of cases are among the California variant, known as B.1.427/B.1.429, and also believed to be more transmissible.

“More than 50% of positive cases that are occurring in the state are now due to variants of COVID-19,” Herlihy said. “If you develop COVID now, chances are that you actually are going to be infected with a variant that is probably more easily spread and could potentially cause more severe illness.”

Herlihy said Colorado has now found 12 cases of the P.1 coronavirus variant first tied to Brazil. The variant was first identified in Colorado earlier this week. It is still being studied but is believed to be more transmissible and harder to treat. It’s also believed to cause more severe illness and more easily reinfect people who have already had a COVID-19 infection.

“We do believe that there have been multiple introductions of P.1 in the state of Colorado,” Herlihy said. “We know that several of the individuals (who have the variant) have a travel history, including one individual who did travel internationally.”

P.1 has been found in Denver, Arapahoe, Boulder and Broomfield counties. There are two household clusters, but Herilhy said “there are additional cases outside of those household clusters.”

“Severe infections can and are occurring in younger populations,” Herlihy said. “It’s another reason why younger people need to be vaccinated as well.” 

While vaccines have been shown to be less effective against some COVID-19 variants, it’s by a small factor. Inoculations can also still prevent severe illness and death. 

The rising cases and hospitalizations come as Colorado Gov. Jared Polis is relaxing statewide mask-wearing restrictions and capacity limits on restaurants and other businesses.

Next week, the state is expected to do away with its dial system and leave restrictions up to counties except for large indoor gathering places, which will continue to be regulated by statewide public health orders.

MORE: Colorado will loosen its coronavirus dial system next week, allow bars to reopen across much of the state and end personal gathering limits

Polis said he isn’t rethinking his plans to do away with the dial system. He expects cases to fall in mountain communities, which have seen a recent spike, as ski season ends.

“The greater concern (is in) the population centers — Denver metro area, Colorado Springs metro area. This is where we really look forward to working with our local partners — mayors, local public health authorities, commissioners — to make sure we tailor that messaging to have the best possible public health impact,” he said.

Polis said Friday that the good news is that he believes this fourth wave will be Colorado’s last wave. “I think it’s the fourth and final wave,” he said.

People 18 to 50 years old are most susceptible right now because only a fraction of that population has been fully vaccinated. 

“This is a time of great concern in Colorado,” Polis said. “That being said we have plenty of (hospital) capacity.”