Having failed to adequately prepare for the second wave of coronavirus infections, officials and health authorities are now routinely warning people of the possibility of a third wave.

What defines a wave in an epidemic, at national and regional levels?



There is no textbook definition of what constitutes a wave in an epidemic. The term is used generically to describe the rising and declining trends of infections over a prolonged period of time. The growth curve resembles the shape of a wave. Historically, the term wave used to refer to the seasonality of the disease. Several viral infections are seasonal in nature, and they recur after fixed time intervals. Infections rise and then come down, only to rise again after some time.