Typhoid Vaccine Recommendations for High-Risk Areas
Typhoid vaccination is strongly recommended for travelers to high-risk endemic areas (particularly the Indian subcontinent, Africa, Asia, and Latin America), household contacts of documented typhoid carriers, and microbiology laboratory workers who handle S. typhi. 1, 2, 3
Who Should Receive Typhoid Vaccination
The CDC identifies three primary groups requiring typhoid vaccination:
- Travelers to endemic regions: Particularly those visiting developing countries in Latin America, Asia, and Africa with prolonged exposure to potentially contaminated food and water 1, 2
- Household contacts: Persons with intimate, continued exposure to a documented typhoid carrier 1, 2, 3
- Laboratory workers: Microbiology personnel who frequently work with S. typhi 1, 2, 3
Geographic Risk Stratification
The highest-risk destinations warrant vaccination:
- Highest risk: India and neighboring countries (41.7 cases per 100,000 travelers) 4
- High risk: Middle East (5.91 per 100,000) and Central/East Africa (3.33 per 100,000) 4
- Lower risk: East Asia (0.24 per 100,000) where routine vaccination may not be necessary 4
Available Vaccine Options
The Vi-TT conjugate vaccine (TCV) should be the first-choice vaccine when available, due to superior long-term efficacy (78% at 4 years), effectiveness in young children, and less frequent boosting requirements. 1
Vaccine Comparison
When TCV is unavailable, choose between two alternatives:
- Vi polysaccharide vaccine (Typhim Vi): Single 0.5 mL intramuscular or subcutaneous dose for ages ≥2 years, with 55% three-year efficacy 1, 2
- Oral Ty21a vaccine (Vivotif): Four enteric-coated capsules taken on alternate days for ages >6 years, with 50-67% efficacy 1, 3, 5
Both alternatives demonstrate 50-80% effectiveness, which is substantially lower than TCV 1, 6
Administration Guidelines
Vi Polysaccharide Vaccine (Injectable)
- Adults and children ≥10 years: 0.5 mL as single dose, subcutaneously or intramuscularly 1, 2
- Children 6 months to <10 years: 0.25 mL subcutaneously, two doses separated by ≥4 weeks 1
- Timing: Administer at least 2 weeks before expected exposure 2
- Boosters: Every 2 years with continued exposure 1, 2
Oral Ty21a Vaccine
- Adults and children ≥6 years: One enteric-coated capsule on alternate days for total of four capsules 1, 3
- Administration technique: Take with cool liquid no warmer than 37°C, approximately 1 hour before meals 1
- Boosters: Repeat entire four-dose series every 5 years 1, 3
Critical Limitations and Precautions
Vaccine Effectiveness Caveats
Vaccination does not replace food and water safety precautions, as no vaccine provides 100% protection and can be overwhelmed by large bacterial inocula. 1, 7
- Demonstrated vaccine effectiveness in US travelers is approximately 80%, meaning 1 in 5 vaccinated individuals remain susceptible 6
- Careful selection of food and beverages remains essential even after vaccination 8, 1, 2
Contraindications and Special Populations
Injectable Vi polysaccharide vaccine:
- Contraindicated with history of severe reaction to previous dose 8
- Should not be used in immunocompromised patients or those with HIV due to inadequate immune response 1
Oral Ty21a vaccine:
- Not recommended for children <6 years of age 8, 3
- Contraindicated in immunocompromised persons, including those with asymptomatic HIV infection 8, 1
Common Pitfalls to Avoid
- Don't assume vaccination eliminates risk: The 50-80% efficacy range means significant breakthrough infections can occur, particularly with high inoculum exposure 1
- Don't use for outbreak control: Typhoid vaccination is not indicated for common source outbreaks, natural disasters, or rural summer camps in the US 8, 2, 3
- Don't confuse with paratyphoid protection: Typhoid vaccines offer no protection against Salmonella Paratyphi A or other enteric pathogens 3, 6
- Don't forget timing: Vaccination must occur at least 2 weeks before travel to allow adequate immune response 2