- Oral Ty21a. The live, attenuated mutant strain of Salmonella typhi Ty21a, supplied in enteric coated capsules, is given in three doses (four doses in North America ), 2 days apart. Protection is induced 7 days after the final dose. After 7 years, the average protective efficacy was shown to be 67% in residents of endemic countries, although the vaccine may be less effective in travellers from non-endemic countries. A previously manufactured liquid formulation is no longer available.
- Injectable Vi CPS. The Vi capsular polysaccharide vaccine (Vi CPS) contains 25 µg of polysaccharide per dose, and is given i.m. in a single dose. Protection is induced about 7 days after the injection. In countries or areas at risk, the protective efficacy 1.5 years after vaccination is about 72% and about 50% after 3 years.
Both typhoid vaccines are safe and effective.
A combined typhoid/hepatitis A vaccine is also available in some countries.
Precautions and contraindications
Proguanil, mefloquine and antibiotics should be stopped from 3 days before until 3 days after the administration of Ty21a.
No serious adverse effects have been reported following administration of Ty21a or Vi CPS.
These vaccines are not recommended for use in infant immunization programmes due to insufficient information on their efficacy in children under 2 years of age.
Type of vaccine: Oral Ty21a and injectable Vi CPS
Number of doses: Three or four doses of live Ty21a, given at 2-day intervals as enteric coated capsules. One dose of Vi CPS, given i.m.
Booster: Every 2–3 years for Vi CPS; for Ty21a, see package insert.a
Contraindications: There are no contraindications to the use of these vaccines other than previous severe hypersensitivity reactions to vaccine components.
Adverse reactions: None significant
Before departure: 1 week
Recommended for: Typhoid fever vaccination may be offered to those travelling to destinations where the risk of typhoid fever is high, especially individuals staying in endemic areas for >1 month and/or in locations where antibiotic resistant strains of S. typhi are prevalent.
Special precautions: Vi CPS – not under 2 years of age; avoid proguanil, mefloquine and antibiotics with Ty21a
a The duration of protection following Ty21a immunization is not well defined and may vary with vaccine dose and possibly with subsequent exposures to Salmonella typhi (natural booster). In Australia and Europe, 3 tablets are given on days 1, 3, and 5; this series is repeated every year for individuals travelling from non-endemic to endemic countries, and every 3 years for individuals living in countries or areas at risk. In North America, 4 tablets are given on days 1, 3, 5, and 7 and revaccination is recommended only after 7 years (Canada) or 5 years (USA) for all, regardless of typhoid fever risk in the country or area of residence.