Pandemic Metrics

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What these dashboards do:

  • In the VDH Pandemic Metrics dashboards:
    • The Daily Region Metrics dashboard shows where COVID-19 is spreading in Virginia and the changes over time.
    • The Weekly Transmission Extent dashboard helps inform state and local officials about the effects of COVID-19 on each region to help them decide whether to act on additional mitigation measures for individual communities.
    • Please see below for Technical Notes and Talking Points
  • VDH also created visualizations to display the CDC School Metrics to help communities and school divisions understand the risk of introduction and transmission of COVID-19 in schools.
    • VDH recommends that communities and school divisions use the CDC Indicators for Dynamic School Decision-Making framework together with VDH Guidance for Mitigation Measures in K-12 Settings when considering actions related to school decision making.

VDH has evaluated the differences between the thresholds that CDC set forth in the Indicators for Dynamic School Decision-Making for case incidence and percent positivity and those thresholds originally used in the creation of the Pandemic Metrics tool. In order to be consistent with national standards, VDH has decided to use the CDC thresholds. However, while the CDC Indicators call for 14-day cumulative statistics, the VDH Pandemic Metrics tool is designed to use a 7-day moving average of daily values for case incidence and percent positivity. In order to translate cumulative thresholds for use at the daily level, they have been divided by 14.

This decision affects some of the previously reported levels of overall burden and overall transmission extent by region. VDH developed the Pandemic Metrics tool in order to bring some of the core data sources together and to calculate an overall measure of COVID-19 activity in the community. Enhancements to this tool are expected and are intended to improve its performance over time.

Differences Between the VDH Pandemic Metrics dashboards and CDC School Metrics 

  • VDH created the VDH Pandemic Metrics dashboards in June 2020. Local health districts began using the dashboards in July and sharing data with localities and schools in August. 
  • On September 15, CDC published the School Indicators for Dynamic Decision Making, which include thresholds for each category and indicator.   
  • The VDH Pandemic Metrics dashboards show a daily case incidence rate and a daily PCR percent positivity. 
    • Rates are used to standardize comparison of regions with populations of varying size in Virginia. 
    • A 7-day moving average is used to smooth out the variability in daily reporting and to remove weekday effects.
    • For case incidence, three levels are set with two thresholds: <5 cases per day per 100,000 population, 5 to <10, and ≥10.
    • For PCR percent positivity, two levels are set with one threshold of ≥10%.
  • The CDC framework utilizes a 14-day cumulative case incidence rate and a 14-day cumulative percent positivity, not daily rates. 
    • Five levels are set for 14-day cumulative case incidence: <5 cases within the last 14 days per 100,000 population, 5 to <20,  20 to <50, 50 to 200, and >200.  
    • Five levels are set for 14-day cumulative PCR percent positivity: <3%, 3% to <5%, 5% to <8%, 8% to ≤10%, and >10%.