Pitkin County has the highest virus rate in the state, again


Here are the three most likely causes


By Alex Hager
Aspen Public Radio

Pitkin County’s COVID-19 incidence rate is the highest in Colorado by a wide margin. As a result, businesses are operating under “orange” level restrictions – a more stringent set of rules than anywhere else in the state.

Even among similar destination resort communities, Pitkin County’s rate is remarkably high. Its two-week incidence rate per 100,000 residents is nearly double the same data point in Summit and Eagle Counties.

If you think you’ve heard this news before, you have. Pitkin County’s virus rates surged ahead of the rest of the state in January. Then, the county’s health leadership was left with only theories as to why.

This time around, the county has identified a new set of reasons it suspects are driving the spike.

The first is the volume of people moving in and out of the county. Mobility data, gathered by tracking the movement of cell phones, is used as a way to measure the number of visitors to the area.

“As we see increasing mobility numbers, about a week later we see increases in our incidence rate,” said Jordana Sabella, Pitkin County public health director.

Mobility data shows a substantial uptick of out-of-state visitors in mid-March, a time that typically sees a swell of visitorship to the area during spring breaks across the nation. Recent data shows more movement in mid-March than President’s Day Weekend.

The idea that tourist visitorship is driving coronavirus transmission among residents likely explains why the three counties with the highest incidence rates in Colorado are the homes of Aspen, Breckenridge and Vail, respectively.

Sabella also posed a theory as to why Pitkin County’s rate is drastically higher than other areas with ski resorts. Because incidence rate is calculated using census data, the official tally of Pitkin residents may be significantly lower than the actual number of people living long-term in the county. A large number of seasonal workers and second homeowners may be living in the county, but not counted in the area’s census data.

Another reason that Pitkin County’s rates are so high could lie in the volume of coronavirus variants present in the area. The county’s epidemiologist reported 30 confirmed cases of variants and 67 suspected. According to the state’s data on variants, Pitkin County has the second-highest rate of variant cases among all counties in the state, when scaled to population. The majority of those cases are the B.1.1.7 variant, commonly referred to as the “U.K. variant.”
The Colorado Department of Public Health and Environment agrees with the county that mobility and variants are major drivers of local virus transmission.

The third suspected reason for Pitkin County’s spike in cases is a rise in informal gatherings as pandemic fatigue is leading people to ignore protocols designed to curb transmission. Partially vaccinated and unvaccinated people meeting together are contributing to the spread of the virus.

“People are tired,” Sabella said.

Charts tracking the number of “contacts” incurred by each cell phone – defined as the number of devices that people come within six feet of for 15 minutes or more – showed people in Pitkin County were having far more interaction with others than the statewide average. In late March, people in Pitkin County averaged about five contacts per day. Across the state, meanwhile, people averaged about two contacts per day.

Despite the surge in cases, Sabella said vaccines are a promising defense against severe illness and hospitalization among infected residents.

“As more of our population becomes immune,” Sabella said. “We will definitely see a different trajectory of incidents across the state and in Pitkin County than we did in January.”

So far, nearly 9,000 Pitkin County residents have received at least one dose of the COVID-19 vaccine. According to census estimates, that represents about half of all people in the county.