COVID-19 is an infectious disease caused by the SARS-CoV-2 virus. Most people with COVID-19 have mild symptoms, but some people become severely ill. Older adults and people who have certain underlying medical conditions are more likely to get severely ill. Post-COVID conditions can include a wide range of health problems that can last four or more weeks after contracting COVID-19. Even those who do not become severely ill from COVID-19 may experience post-COVID conditions, sometimes referred to as Long COVID. For more information, visit the Centers for Disease Control and Prevention’s (CDC) Basics of COVID-19.