pandemic – n. occurrence of disease that spreads very quickly and affects a large number of people over a wide area or throughout the world

contagious – adj. able to be passed from one person or animal to another by touching

symptom – n. a physical feeling or problem that indicates a person has a particular illness

cough – n. physical condition or illness that causes someone to cough

avian – adj. of or relating to birds

peak – v. to reach the highest level