Answer
Primary immune response is initiated when some new antigenic substance is detected for the first time. Since this is the first time the body got this antigen it will take longer time to find a solution for it. Generally it takes 4 to 5 days for the primary immune response to complete.
Secondary immune response is initiated when some previously encountered antigens are detected. The memory cells already have the information regarding these cells so this acts faster than primary immune response. This will take only 2 to 3 days to complete.
Work Step by Step
Same as above.
