A pandemic is a worldwide spread of a new disease, such as a new influenza virus or the coronavirus COVID-19
. It is not the same as an epidemic, which is when many more cases of a health condition occur than would normally develop in a community or region, but the condition does not spread further
. Pandemics are most often caused by viruses which can easily spread from person to person
. The World Health Organization (WHO) is responsible for declaring when a global pandemic is occurring
. The number of lives lost in a pandemic depends on how many people are infected, how severe of an illness the virus causes, how vulnerable certain groups of people are, and prevention efforts and how effective they are
