You have given ViPS vaccine to a person. How often will you ask him to take booster doses?

The injectable typhoid vaccine ViPS is a single dose vaccine which requires booster doses every 3 year. Ty21a vaccine is the oral typhoid vaccine. 3 doses are taken on day 1,3 and 5. It is effective for up to 7 years after last dose. It is recommended in people travelling to endemic areas and during out breaks. Ref: Park, Edition 21, Page - 215