Parameter values that vary across the five COVID-19 Pandemic Planning Scenarios (Table 1) include measures of viral transmissibility, disease severity, and pre-symptomatic and asymptomatic disease transmission. Where sufficient data are available, age-stratified estimates are provided.
Viral Transmissibility
- Basic reproduction number (R0): The average number of people that one person with COVID-19 is likely to infect in a population without any immunity (from previous infection) or any interventions. R0 is an estimate of how transmissible a pathogen is in a population.
Disease Severity
- Symptomatic Case Fatality Ratio: The number of symptomatic individuals who die of the disease among all individuals experiencing symptoms from the infection. This parameter is not necessarily equivalent to the number of reported deaths per reported cases, because many cases and deaths are never confirmed to be COVID-19, and there is a lag in time between when people are infected and when they die. This parameter reflects the existing standard of care and may be affected by the introduction of new therapeutics.
- Symptomatic Case Hospitalization Ratio: The number of symptomatic individuals who are hospitalized from the disease among all individuals experiencing symptoms from the infection. This parameter is not necessarily equivalent to the number of reported hospitalizations per reported cases, because many cases and deaths are never confirmed to be COVID-19, and there is a lag in time between when people are infected and when they die. This parameter reflects the existing standard of care and may be affected by the introduction of new therapeutics.
