Each scenario is based on a set of numerical values for biological and epidemiological characteristics of COVID-19. These values—called parameter values—can be used to estimate the possible effects of COVID-19 in U.S. states and localities. The parameter values in each scenario will be updated and augmented over time, as we learn more about the epidemiology of COVID-19.
New data on COVID-19 is available daily; information about its biological and epidemiological characteristics remain limited, and uncertainty remains around nearly all parameter values.
The parameters in the scenarios:
- Are estimates intended to support public health preparedness and planning.
- Are not predictions of the expected effects of COVID-19.
- Do not reflect the impact of any behavioral changes, social distancing, or other interventions.