A widespread outbreak is an epidemic, which is defined as a contagious disease that spreads rapidly and affects many people. An epidemic can occur in a localized area or across a wide region, and can be caused by a variety of factors, such as a new virus or bacteria, environmental changes, or even human behavior. In recent years, there have been several large-scale epidemics, including the Ebola virus, Zika virus, and SARS-CoV-2, which causes COVID-19.