A surveillance report states that there have been 2,000 cumulative cases of COVID-19 in the United States since 2020. This figure best represents which epidemiologic measure?

Incidence counts new cases occurring over a defined period. Reporting cases accumulated 'since 2020' describes new cases arising over time, which is incidence.Other options: Prevalence is the proportion of existing cases at a single point in time. Attack rate and mortality rate are not what a cumulative new-case count over a period represents.Key exam takeaway: Incidence = new cases over a time period. Prevalence = all existing cases at one moment.