When local health staffers are alerted to new cases of coronavirus in Pitkin County, they work with infected people to figure out where they might have picked it up. 39% of cases in the county are considered “community spread,” meaning the infected person does not know where they were exposed to the virus.
Pitkin County epidemiologist Josh Vance said that number has stayed around 40% “pretty consistently for a while.”
“We have a significant amount of individuals out there that we’re unaware of,” Vance said. “We don’t know if we just missed them, if they didn’t get tested, if they live in a different community."
"But 40% of individuals are claiming exposure to someone that we don’t have record of.”
The volume of “community spread” cases is likely due in part to the number of people who enter and exit the county. High tourist traffic and a workforce commuting from out-of-county may be making it harder to identify the source of some new infections.
“It’s one of those indicators that I think we’re going to have a hard time reducing,” Vance said. “Not to the fault of anyone in Pitkin or our public health order. I think with the amount of travel and in-and-out visitors, we may expect to see that rate stay pretty high.”
Vance said cases with unknown origin make it hard for contact tracers to track further spread, and for policymakers to target certain groups or activities with messaging that might help stymie future transmission.
The second largest category of coronavirus spread was within households. 27% of new infections were traced to other members of the same household. The third largest was “informal gatherings,” such as parties and get-togethers, which accounted for 9% of new cases.
At Thursday's county board of healh meeting, Vance also presented two other datasets related to virus transmission in Pitkin County. In a chart showing the geographic breakdown of out-of-town cases, 43% of all infected out-of-towners were residents of other Colorado counties. 20% were residents of Texas, 11% were residents of Florida and 9% were residents of California.
In another chart, Vance explained that cases of coronavirus are disproportionately affecting Hispanic and Latinx people. More than 30% of August cases have affected Hispanic/Latinx people, but Hispanic/Latinx people only make up about 10.5% of Pitkin County’s population. The proportion of cases in Pitkin County’s Hispanic/Latinx residents has risen steadily since March.