"Year duration" refers to the length of one full year, usually consisting of 365 days (or 366 days in a leap year). It simply describes the amount of time it takes for the Earth to complete one orbit around the sun. Full definition
Adults: The first rabies vaccine has a one year duration of immunity with yearly booster vaccines thereafter. (harmonyanimalvet.com)
We use the highest quality vaccines available and use three year duration vaccines when possible. (litchfieldvet.com)
What I've noticed is that many people I've seen with psoriasis of several years duration also complain of sore and tight muscles, and these muscles can differ from person to person. (ericbakker.com)