A pandemic ( from Greek πᾶν pan `` all '' and δῆμος demos `` people '' ) is an epidemic of infectious disease that has spread through human populations across a large region ; for instance multiple continents , or even worldwide .
A pandemic ( from Greek παν pan all + δήμος demos people ) is an epidemic ( an outbreak of an infectious disease ) that spreads across a large region ( for example a continent ) , or even worldwide .