Won't be unvax and lose total vaccination. Just need to take booster when you are ready and the fully vax status will be back! If you did not manage to get your booster in time, your Vaccination status will turn grey and show ‘Additional dose needed’. To get a green ‘Vaccinated’ status again, you need to get a booster. We recommend you to take your booster as soon as you become eligible for it. While there’s no 14-day waiting period for boosters to take effect, the systems may take 1-3 days to update that you’ve taken your booster. https://support.tracetogether.gov.sg/hc/en-sg/articles/4414514534681--Booster-I-have-not-taken-my-booster-When-might-my-Vaccinated-status-expire-