Typhoid Vaccine Studies: Revaccination and Duration of Immunity

Abstract
One intracut. injn. is usually sufficient to re-establish immunity in previously vaccinated individuals, as judged by the mouse-protective powers of these individuals'' sera. Revaccinated persons tend to retain high protective titres longer than those who have had fewer or only one course, but it is recommended that not more than 2 yrs. elapse between courses.