What is the recommended prophylaxis for typhoid fever prevention?

Typhoid Fever Prophylaxis Recommendations

For typhoid fever prevention, the recommended prophylaxis is oral live-attenuated Ty21a vaccine (four capsules taken every other day) or the Vi capsular polysaccharide parenteral vaccine (single intramuscular dose), with vaccination indicated for travelers to endemic areas, persons with intimate exposure to typhoid carriers, and laboratory workers who frequently work with S. typhi. 1

Vaccine Options and Administration

Oral Live-Attenuated Ty21a Vaccine

• Adults and children ≥10 years of age:
  • One enteric-coated capsule taken on alternate days to a total of four capsules
  • Each capsule should be taken with cool liquid no warmer than 37°C
  • Take approximately 1 hour before meals
  • Capsules must be kept refrigerated
  • All four doses must be taken to achieve maximum efficacy 1
  • Booster doses recommended every 5 years with continued exposure 1

Vi Capsular Polysaccharide Parenteral Vaccine

• Adults and children ≥2 years: Single 0.5 mL intramuscular dose
• Booster doses required every 2 years with continued exposure 1

Target Populations for Vaccination

Typhoid vaccination is indicated for:

• Travelers to areas with recognized risk of exposure to S. typhi (especially Latin America, Asia, and Africa) 1
• Persons with intimate exposure to documented typhoid fever carriers 1
• Workers in microbiology laboratories who frequently work with S. typhi 1

Vaccine Efficacy and Safety

Efficacy

• Both vaccines protect 50-80% of recipients 1
• Ty21a vaccine has demonstrated 62% protection over seven years of follow-up 2
• Vi polysaccharide vaccine provides 75-80% protection 3

Safety

• Oral Ty21a vaccine: Side effects are rare (8.9% reported minor side effects) and include abdominal discomfort, nausea, vomiting, and rash 1, 4
• Vi polysaccharide vaccine: Lower reactogenicity compared to older parenteral vaccines 3
• Serious adverse events requiring hospitalization are rare (0.47 to 1.3 per 100,000 doses) 1

Important Precautions and Contraindications

• Live-attenuated Ty21a should not be used in immunocompromised persons, including those known to be infected with HIV 1
• Theoretical concerns exist about Ty21a immunogenicity in persons concurrently receiving antimicrobials (including antimalarial prophylaxis), viral vaccines, or immune globulin 1
• The only contraindication to parenteral vaccination is a history of severe local or systemic reactions following a previous dose 1

Compliance Considerations

• Compliance with Ty21a administration instructions is critical for efficacy:
  • 30% of travelers may not fully comply with all instructions 4
  • Common compliance issues include taking doses after meals (21.6%), not taking all doses (8.3%), incorrect timing between doses (6.4%), and improper refrigeration (3.2%) 4
  • Emphasize to patients the importance of following all administration instructions 4, 5

Additional Prevention Measures

• Typhoid vaccination is not a substitute for careful selection of food and drink 1
• Proper hand hygiene and food safety practices are essential 6
• Avoid high-risk foods and beverages in endemic areas 6

Clinical Pearls

• Typhoid vaccines are not 100% effective and protection can be overwhelmed by large inocula of S. typhi 1
• Routine typhoid vaccination is not recommended in the United States 1
• Typhoid vaccine is not indicated for controlling common-source outbreaks or for persons in areas with natural disasters 1
• When traveling to areas with high typhoid prevalence, vaccination should be completed at least 1-2 weeks before departure for optimal protection