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DENVER (KDVR) — The trend is clear among Colorado’s populous Front Range counties: the higher the vaccination rate, the lower the incidence of COVID-19.

Outside of that, the trend gets hazy.

Vaccination rates have inched upward in Colorado since hitting their bottom in mid-July. The state now vaccinates an average 8,500 people a day, or about a 1,000 more people than a month ago.

Nationally, there is a clear divide between a state’s vaccination rates and its case rates. A Wall Street Journal analysis of the country’s COVID data found that every state with a vaccination rate less than the U.S. rate had a higher COVID case rate, and vice versa.

Colorado’s Front Range counties follow the same pattern, though outliers appear as more counties enter the picture.

Generally, a county’s two-week cumulative incidence rate goes down as its rate of people vaccinated with at least one dose goes up.

El Paso and Weld counties both have lower vaccination rates than Front Range neighbors and higher cumulative incidence rates.

As the vaccination rate improves, the one-week incidence rate goes down. Boulder County has the highest vaccination rate among Front Range counties at over 80% and also the lowest incidence rate at 84 cases per 100,000.

This trend is holds true for the counties in which over 80% of the state’s population lives.

The trend gets murkier as more counties enter the picture.

Outliers complicate the picture when all Colorado counties over 100,000 are considered.

Pueblo County has an equivalent vaccination rate to El Paso and Weld counties, but unlike them, has some of the lowest incidence rates of Colorado’s most populated counties.

Even more outliers pop up if all counties with more than 30,000 people are considered.

In this view, some outliers would appear to completely reverse the Front Range’s trend of high vaccination rates leading to low incidence rates.

Morgan, Elbert and Teller counties have even lower vaccination rates than Pueblo county, but also have lower incidence rates. Meanwhile, Summit and Eagle counties have both some of the state’s highest vaccination rates and the highest incidence rates.

Many factors could contribute to this disparity — tourism and intrastate destination travel, geographic isolation and population size all play a role. Trends become clearer with larger numbers, like Colorado’s Front Range counties trend of lower COVID rates among highly vaccinated counties.