New COVID-19 Testing Trends Tool
States across the United States have taken steps to mitigate the spread of SARS-CoV-2, the virus that causes COVID-19, such as instituting stay at home orders or physical distancing measures. Decisions on when to ease these mitigation efforts consider several important metrics including daily case counts, the number of diagnostic tests conducted per population, and the percent of those tests that are positive for SARS-CoV-2, among others.
No single metric is sufficient for understanding the reach of SARS-CoV-2 in an area. For example, daily case counts could increase because disease transmission is increasing (meaning the pandemic is getting worse) or because more test kits have become available enabling previously undetected cases to be identified. Our testing capacity is now greater than in the first months of the pandemic and the number of people utilizing these services is changing daily. This means our ability to discern whether COVID-19 is increasing, stable, or decreasing requires more detail about the number of tests being performed and the proportion of those tests that are positive. Therefore, several metrics must be monitored and evaluated together to be able to evaluate the status of the pandemic.
IVAC partnered with Graphicacy, a visual design team based in Washington, D.C., to bring together metrics on diagnostic testing rates, the number of positive cases, and the percent of tests that are positive to help understand the state of the pandemic in each state.
These charts lay out the key metrics for understanding the reach and severity of COVID-19 in a given area: number of new daily cases, tests per 100,000 people (testing rate), and percentage of tests that are positive (positivity rate).
As testing capacity increases, considering confirmed new cases, testing rates, and percent positivity together gives us a fuller picture of COVID-19 in a particular state or region. Ideally, a state should be meeting or exceeding the recommended testing rate appropriate for its disease incidence and less than 5% of tests should be positive. Under these conditions and stable testing practices, trends in daily cases can be cautiously interpreted as trends in transmission of the virus. Leaders can then make informed decisions about lifting social distancing and other transmission control measures.
About the Data
- New cases are presented as daily counts as reported by the state and as a 7-day moving average. Due to fluctuations in daily reporting, testing rates are presented as 7-day rolling averages only.
- As guidance evolves on COVID-19 case reporting, some states are modifying their reporting to include both confirmed cases, based on laboratory testing, and probable cases, based on specific criteria for symptoms and exposure. This may cause new case data to “spike.”
- It is important to note that the quality of testing data varies by state. Click here for more.
Conceptualized by: International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health (www.jhsph.edu/ivac/): Melissa Higdon, Maria Deloria Knoll, Maria Garcia Quesada, Julia Bennett
Click here to view the tracker