April 1, 2020

COVID-19 Trends

COVID-19 Trends

The information above helps to identify regions that may be experiencing changes in key COVID-19 metrics. Using a series of 7-day moving averages, green, yellow, and red colors identify decreasing, inconclusive, or increasing trends, respectively. A second map provides per capita positive rates (per 100,000 people), placing all regions (county or ISDH district) into 4 equal groups by quartiles, ranging from low to high per capita positive rates. Bar charts to the right of each map below show daily counts for each metric. Trend indicators are designed to highlight regions for further review, and are not intended to predict future trends. We are working daily to augment these data, so the numbers above may change as additional data become available.

Trending logic. The trend indicator uses 3-element vector composed of the differences (represented as increase, decrease, or no change) between four consecutive 7-day averages. Each unique vector is mapped to one of three labels: Green – decreasing trend, Red – increasing trend, Yellow – inconclusive trend.

Data Delay. Receipt of clinical data can be delayed up to three days after the clinical event. Because of this delay, initial counts may be lower than actual counts, which may bias the trend indicator toward green. To avoid this bias, the trend indicator color will not reflect the most recent three days.

Early warning indicator. If a notable increase in daily counts is observed in the most recent three days, a red dot is displayed. A “notable increase” is defined as any individual count in the most recent three days that exceeds the average of the 7 days preceding the three days.

Small number rule. When all daily counts over the entire observational period are 3 or less, the trend is labelled green. This is in addition to the above trending logic.

Per Capita Positive Rates. The per capita rate is computed by dividing the number of positive cases in a region (state, county, district) by the total population for that region, then multiplying by 100,000.

Trend Color definitions
Red – Indicates a pattern of increasing daily counts
Yellow – Indicates an inconclusive pattern, neither clearly increasing or decreasing.
Green – Indicates a pattern of decreasing daily counts or low daily counts.