We (2 adults and one 6 years old kid and one 7 years old kid) are leaving saudi arabia soon to go back and live in canada. should we get seasonal flu shots in saudi arabia before departure or should we get those in canada. ?

Either. In September: Either country. No rush. Shots Sep. 1 to Oct. 15 is fine. Kids under age 9 years get 2 flu vaccines their first year of getting flu vaccines. The reason for 2 flu vaccines is to boost antibody levels, because these first-timers don't have memory of any flu vaccines in their immune systems. The do get protection from just one vaccination, but 2 vaccines give better protection.