All scores/measures must be considered collectively. While [for example] an infection rate might be low, a high positive test rate would suggest that testing in Douglas County, Nebraska is limited and that most cases may go undetected. At these levels, it is hard to know how fast COVID is actually spreading, and there is risk of being surprised by a second wave of disease. When that is true, continued caution is warranted.
You can find out more about Covid Act Now here.