The time interval between the primary and secondary case is :
Ans. is 'a' i.e. Serial interval Serial intervalThe gap in time between the onset of the primary case and the secondary case is called the serial interval.Generation time is the interval of time between receipt of infection by a host and maximal infectivity of that host.Median incubation periodis the time required for 50 percent of the cases to occur following exposure.
Serial interval
Generation time
Median Incubation period
Secondary attack rate
Infectious Disease Epidemiology