Ans. is 'd' i.e., Typhoid Antityphoid vaccineso Two safe and effective vaccines are licensed and available1) The Vi polysaccharide vaccine (TYPHIM Vi Vaccine)# It contains purified Vi capsular polysaccaride from Ty2 strain.# It is given as single dose by subcutaneous or intramuscular route.# It confers protection 7 days after the injection.# To maintain protection, re-vaccination is recommended every 3 years.# It is given in individuals >2 years of age (not given < 2 years of age).# The vaccine can be co-administered with other vaccines relevant for international travellers, e.g. yellow fever and hepatitis A.# The vaccine has no serious systemic or local side effects. There is no major contraindication, except for hypersensitivity.2) The Ty 21a Oral vaccine (TYPHORAL Vaccine)# It is an orally administered live attenuated vaccine.# It contains > 109 viable organisms of live attenuated Ty 21a strain which lacks enzyme UDP-galactose-4- epimerase (Gal E mutant).# Vaccine is administered on /, 3 and 5th day, i.e. a 3-dose regimen.# Vaccine conferes the protection 7 days after the last dose.# The recommendation is to repeat the series (3 doses) every 3 years for people living in endemic areas and every year for individuals travelling from non-endemic to endemic countries.o The 'old' heat killed phenol extracted whole cell vaccines are not used now because of strong side effects. These vaccines were monovalent (contains S. typhi), bivalent (contains S. typhi and S. paratyphi A), and TAB vaccine (contains S. typhi, S. parathyphi A and S. paratyphi B).