COVID-19 is a respiratory condition caused by a coronavirus. Some people are infected but don’t notice any symptoms (doctors call that being asymptomatic). Most people will have mild symptoms. Johns Hopkins experts in global public health, infectious disease, and emergency preparedness have been at the forefront of the international response to COVID-19. This website is a resource to help advance the understanding of the virus, inform the public, and brief policymakers in order to guide a response, improve care, and save lives. Jun 14, 2021 · Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus. Most people infected with the virus will experience mild to moderate respiratory illness and recover without requiring special treatment. However, some will become seriously ill and require medical attention..