Serial interval is the gap between-
.serial interval is the time gap between the development of primary case and the fuher introduction of the disese agent into the community to cause secondary infections.from this we get a distribution of of secondary cases from which we can guess the incubation period of disease. ref:park&;s textbook,ed22,pg 95
Primary and secondary case
Index and primary case
Introduction of infection and development of maximum infectivity
Transmission infection from patient to another susceptible host
Epidemiology