What are the names of the typhoid vaccines approved for adult use?

Typhoid Vaccines for Adults

For adults, two main typhoid vaccines are available: Ty21a (oral live-attenuated vaccine) and Vi polysaccharide (injectable vaccine), with newer typhoid conjugate vaccines (TCVs) including Vi-TT (Typbar-TCV) now recommended by WHO as the preferred option across all ages.

Available Vaccine Types

1. Ty21a (Oral Live-Attenuated Vaccine)

• Brand name: Vivotif (commonly known)
• Formulation: Enteric-coated capsules
• Dosing for adults: Four capsules taken on alternate days (total of 4 doses) 1
• Administration: Each capsule taken with cool liquid no warmer than 37°C, approximately 1 hour before meals
• Storage: Must be kept refrigerated
• Efficacy: Prevents approximately 50% of typhoid cases over 2.5-3 years (cumulative efficacy: 50%, 95% CI 35% to 61%) 2
• Booster: Repeat entire four-dose series every 5 years 1

2. Vi Polysaccharide Vaccine (Injectable)

• Formulation: Parenteral inactivated vaccine
• Dosing for adults: Single 0.5 ml dose subcutaneously 1
• Efficacy: Prevents approximately 69% of cases in year 1 (95% CI 63% to 74%), declining to 59% in year 2 (95% CI 45% to 69%) 2
• Booster: Every 3 years under continued exposure 1

3. Typhoid Conjugate Vaccines (TCVs) - Newer Generation

Multiple Vi-conjugate vaccines are now available:

• Typbar-TCV (Vi-TT: Vi-tetanus toxoid conjugate)

  • WHO-prequalified and recommended as preferred vaccine 3, 2
  • Single intramuscular dose
  • Efficacy at 2 years: 83% (95% CI 77% to 87%) 4
  • Approved for adults up to 45 years in India 5

• TyphiBEV (Vi-CRM197 conjugate)

  • Demonstrated non-inferiority to Typbar-TCV 6
  • Single dose administration

• Vi-rEPA (Vi-recombinant Pseudomonas aeruginosa exotoxin A)

  • Two-dose schedule
  • Efficacy: 94% in year 1,87% in year 2 4, 2
  • Limited availability

Key Clinical Considerations

Vaccine Selection Algorithm:

• Immunocompetent adults: Typbar-TCV (Vi-TT) is preferred given superior efficacy (83% at 2 years) and single-dose convenience 4, 3
• Immunocompromised patients: Use Vi polysaccharide or Vi-conjugate vaccines; avoid Ty21a (live vaccine contraindicated) 1
• Limited time before travel: Vi polysaccharide or TCV (single dose) preferred over Ty21a (requires 4 doses over alternate days)
• Pregnancy: No safety data available for any typhoid vaccine; use only if benefits clearly outweigh risks 1

Safety Profile Comparison

Ty21a: Minimal adverse effects—comparable to placebo for GI symptoms, headache, and rash; slightly increased fever risk 2

Vi polysaccharide: Local reactions common (pain and swelling at injection site); fever rates similar to placebo 2

TCVs: Comparable safety to other typhoid vaccines; no serious adverse events reported in trials 4, 3

Important Caveats

• Ty21a must be refrigerated and all four doses completed for maximum efficacy 1
• No typhoid vaccine is 100% effective—careful food and water precautions remain essential 1
• Vaccines do not protect against paratyphoid fever 1
• Gut-selective biologics (e.g., vedolizumab): Limited data suggest live vaccines may be considered if benefits outweigh risks, though this remains controversial 7