Is it necessary to start a vaccine series over if a patient doesn’t come back for a dose at the recommended time, even if there’s been a year or more delay?

For routinely administered vaccines, there is no vaccine series that needs to be restarted because of an interval that is longer than recommended. In certain circumstances, oral typhoid vaccine (which may be given for international travel) needs to be restarted if the vaccine series isn’t completed within the recommended time frame.