Pitkin County's virus rate is the worst in the state, nearly double that of the next highest county. Other counties with destination ski resorts – Eagle, Routt and San Miguel – are among the worst 15, but still pale in comparison to Pitkin County’s rates. Alex Hager / Aspen Public Radio Pitkin County has the highest incidence rate of COVID-19 in all of Colorado, nearly double that of the next highest county. Those alarmingly high numbers have sparked strict public health measures and strained contact tracers – but experts cannot pin down what’s driving the spike. “We ran hundreds of calculations trying to determine what is really the difference here in Pitkin County, what is leading to this increase–and we didn’t really find anything,” said Josh Vance, an epidemiologist for the county.