Duration of immunity after typhoid vaccination is for -: (A) 3 years, (B) 5 years, (C) 7 years, (D) 6 months
Answer is A. <p>Vi polysaccharide vaccine:- Composed of purified Vi capsular polysaccharide from Ty2 S. Administration- subcutaneous/ intramuscularly. Age group more than 2 years. Only one dose required. Confers protection 7 days after injection. Efficacy-85% Duration of immunity-3yrs. To maintain protection,revaccination recommended every 3 years. {Reference: park&;s textbook of preventive and social medicine, 23rd edition, pg no.237}</p>