The effective reproductive number R_t is the average number of secondary cases per infectious case in a population made up of both susceptible and non-susceptible hosts. It also is the number of people in a population who can be infected by an individual at any specific time. If R_t > 1, the number of cases will INCREASE, such as at the start of an epidemic. If R_t = 1, the disease IS ENDEMIC. If R_t < 1, there will be a DECLINE in the number of cases.