Who should receive the typhoid vaccine and what are the recommendations for its administration?

Typhoid Vaccine Recommendations

Typhoid vaccination is selectively indicated for travelers to endemic areas (especially Latin America, Asia, and Africa), persons with intimate exposure to documented typhoid carriers, and microbiology laboratory workers who frequently work with Salmonella typhi. 1

Who Should Receive Typhoid Vaccination

Typhoid vaccination is not routinely recommended for the general population in the United States but is selectively indicated for specific high-risk groups:

• Travelers to areas with recognized risk of exposure to S. typhi, particularly those visiting developing countries in Latin America, Asia, and Africa who will have prolonged exposure to potentially contaminated food and drink 1
• Persons with intimate exposure to a documented typhoid fever carrier, such as those with continued household contact 1
• Workers in microbiology laboratories who frequently work with S. typhi 1

Typhoid vaccination is NOT indicated for:

• Routine use in the general US population 1
• Sewage sanitation workers (except in areas with endemic typhoid fever) 1
• Persons attending rural summer camps 1
• Areas experiencing natural disasters such as floods 1
• Control of common-source outbreaks 1

Available Vaccine Types

Two types of typhoid vaccines are generally available for civilian use in the United States:

1. Oral live-attenuated Ty21a vaccine (Vivotif) 1

   • Efficacy: Reduces laboratory-confirmed infection by approximately 67% for at least 4 years 1
   • Advantages: Similar efficacy to parenteral vaccine with fewer adverse reactions 1

2. Parenteral heat-phenol-inactivated vaccine 1

   • Efficacy: 51%-76% effective in preventing typhoid fever 1
   • More frequent adverse reactions compared to oral vaccine 1

Administration Recommendations

Primary Vaccination

For adults and children ≥10 years of age:

• Oral live-attenuated Ty21a vaccine: 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, approximately 1 hour before a meal. Capsules must be kept refrigerated, and all four doses must be taken to achieve maximum efficacy 1

OR

• Parenteral inactivated vaccine: 0.5 ml subcutaneously, given on two occasions, separated by ≥4 weeks 1

For children <10 years of age:

• Oral live-attenuated Ty21a vaccine: Same dosage as adults (four capsules on alternate days) 1

OR

• Parenteral inactivated vaccine: 0.25 ml subcutaneously, given on two occasions, separated by ≥4 weeks 1

Booster Doses

• For parenteral vaccine: Booster doses should be given every 3 years under conditions of continued or repeated exposure 1
• For oral Ty21a vaccine: The manufacturer recommends revaccination with the entire four-dose series every 5 years, though efficacy has been shown to persist for 5 years with the four-dose regimen 1

Important Considerations and Precautions

• Typhoid vaccination is not a substitute for careful selection of food and drink since the vaccines are not 100% effective and protection can be overwhelmed by large inocula of S. typhi 1, 2

• Vaccine effectiveness: Studies have shown approximately 80% effectiveness in US travelers to endemic regions 3

• Contraindications:

  • For inactivated typhoid vaccine: History of severe local or systemic reaction after a previous dose 1
  • For oral typhoid vaccine: Not recommended for children <6 years of age or immunocompromised persons, including those with asymptomatic HIV infection 1

• Adverse reactions:

  • Parenteral vaccine: Local pain and swelling, fever, headache, and malaise 1, 2
  • Oral vaccine: Rare adverse reactions (<1/100,000 doses) including nausea, abdominal cramps, vomiting, and skin rash or urticaria 1

• Newer vaccines: Vi-conjugate vaccines are being developed and evaluated with potentially improved efficacy, particularly for children 4, 5

Remember that typhoid fever remains a significant health concern for travelers to endemic regions, with the greatest risk associated with travel to countries like Peru, India, Pakistan, and Chile 2. Proper vaccination combined with careful food and water hygiene practices provides the best protection against this disease.