Joint WHO/UNICEF statement for typhoid vaccine use in tsunami-affected areas
- Increased antimicrobial resistance of Salmonella typhi emphasizes the need to use safe and effective vaccines to prevent typhoid fever.
- The old parenteral heat-inactivated whole-cell (WC) typhoid vaccine is effective (above 51%) but associated to frequent and strong adverse reactions.
- Two different types of licensed typhoid vaccines confer good protective efficacy (above 55%) without significant side-effects; these vaccines induce protective immunity for several years.
- Vaccination of high risk populations is considered a most promising strategy for prevention and control of typhoid fever, while being considered as an additional tool to priority control measures such as provision of safe water and proper sanitation.
Currently commercially available typhoid vaccines (Annex 1)
- Single dose vaccine based on purified Vi polysaccharide of S. typhi (Typhim Vi®; Typherix®).
- Administered intramuscularly as 1 dose to individuals aged >2 years.
- Protective efficacy is reached 14-20 days after injection.
- A booster is recommended every 3 years.
- Oral vaccine containing live-attenuated strain Ty21a (Vivotif®) is presented as coated capsules given in 3 doses every other day to individuals >5 years of age.
- Protective efficacy is elicited 10 days after the third dose.
- A booster dose is recommended every 3 years.
None of these vaccines confers protection against paratyphoid fever.
1Typhoid vaccines. Weekly Epidemiological Record 2000; 75:257–64