Typhoid fever is a systemic bacterial illness with fecal-oral transmission characterized by fever and abdominal symptoms. Salmonella enterica Typhi infection is prevalent in many areas of Asia, Africa, and Latin America, and drug-resistant strains of S. Typhi are increasingly prevalent globally. Available vaccines for protection against S. Typhi include
None is completely effective against S. Typhi, and none provides protection against paratyphoid fever; protection against extensively drug-resistant strains of S. Typhi in Pakistan is likely but not well studied.[1]
Typhoid vaccination is recommended for travelers to areas with a risk of exposure to S. Typhi. Incidence of typhoid fever appears to be decreasing in the Americas, Southeast Asia, and some parts of Africa; recommendations for vaccination to these countries from most authorities remain cautious. The risk of acquiring typhoid fever increases with the duration of stay, although travelers have become ill during visits of less than one week to regions where the disease is endemic. Travelers visiting friends and relatives seem to be at particularly high risk of infection. A list of countries is available on the CDC website. [1]
The oral typhoid vaccine is a live attenuated vaccine so should not be administered to individuals with immunodeficiency, acute febrile illness, or acute gastrointestinal illness. Many experts avoid its use in pregnancy and in individuals with chronic intestinal issues including irritable bowel syndrome. [1]
The parenteral polysaccharide Vi vaccine is administered as a single 0.5 mL intramuscular injection (age ≥2 years). A booster dose is recommended two years later in the United States and three years later in Canada and many other countries.
The oral typhoid vaccine is administered as a four-dose course (days 1, 3, 5, and 7) for age ≥6 years and is supplied as a packet of enteric-coated capsules that must be kept refrigerated. The primary course needs to be repeated five years after initial administration. It is acceptable to administer other live vaccines concurrently with the oral typhoid vaccine.
The oral typhoid vaccine should not be administered within 72 hours of antibiotics. The antimalarial drugs atovaquone-proguanil, mefloquine, and chloroquine may be given concurrently with the oral typhoid vaccine at doses used for malaria chemoprophylaxis.
Typhoid fever prevention (immunization):
Oral:
Vivotif: Children ≥6 years and Adolescents: Primary immunization: Oral: One capsule (viable S. typhi Ty21a 2-10 × 109 colony-forming units) every other day for 4 doses (ie, days 1, 3, 5, and 7); all doses should be completed at least 1 week prior to potential exposure. Note: Optimal booster schedule has not been established; in trials, efficacy has been observed for at least 5 years. It is recommended to repeat primary immunization (all 4 doses) every 5 years for repeated or continued exposure. Canadian labeling allows use in children ≥5 years of age and recommends re-immunization every 7 years.
IM:
Typhim Vi: Children ≥2 years and Adolescents: Primary immunization: IM: 0.5 mL administered at least 2 weeks prior to expected exposure. Note: Optimal booster schedule has not been established; in trials, efficacy was reported for the 3-year trial duration. It is recommended to repeat primary immunization every 2 years if exposure is repeated or continued. Canadian labeling recommends re-immunization every 3 years.
Freedman, Leder. Immunizations for travel. Uptodate