pandemic– n. when a disease spreads quickly among a large number of people over a wide geographic area

sustainable– adj. able to be continued without causing severe problems or using up resources

outbreak– n. the sudden appearance of a disease or conflict

herd immunity– n. when a large part of a population cannot become infected with a disease because they have immunity to it

lockdown– n. a security measure of keeping prisoners in their cells; a situation when people are not permitted to go out for a safety-related reason

functioning– adj. to work or operate