I vividly remember having to carry Cholera, Typhoid and Yellow Fever inoculation certificates along with my passport for travelling to Malta in 1967 and to Singapore in 1969. The certificates were closely perused at the Health Check, between passport control and customs. We were required to keep all our "jabs" up to date at all times in case of a need to travel on detachment anywhere in the world at short notice. Cholera was renewed every sx months, Typhoid at two years, I think, and Yellow Fever was good for ten.