Thanks- My certificate notes the vaccination being valid till 2023. However, in 2016, The WHO updated its regulations that made the vaccination valid for life, including for people who had had an expiration date noted on their pre-2016 vaccination.

https://www.who.int/docs/default-sou...st-2020-en.pdf

(last part of point 1, at the top of page 2- revaccination/booster cannot be a requirement)