Usage
- Medical Conditions: Salmonella Typhi vaccine is prescribed for active immunization against typhoid fever caused by Salmonella enterica serovar Typhi (formerly Salmonella typhi). It is recommended for individuals traveling to typhoid-endemic areas, those with intimate exposure to a documented S. Typhi carrier, and laboratory personnel frequently handling S. Typhi.
- Pharmacological Classification: Vaccine.
- Mechanism of Action: This vaccine stimulates an immune response against the Vi capsular polysaccharide of Salmonella Typhi. The Vi antigen is a virulence factor of S. Typhi. By eliciting an immune response, the vaccine primes the body to fight against S. Typhi infection upon exposure.
Alternate Names
- Typhoid Vi Polysaccharide Vaccine (ViCPS).
- Brand Names: Typhim Vi.
How It Works
- Pharmacodynamics: The vaccine generates a predominantly humoral immune response, stimulating the production of specific antibodies against the S. Typhi Vi polysaccharide. These antibodies mediate opsonization and complement activation, leading to bacterial clearance.
- Pharmacokinetics: The vaccine is administered intramuscularly. After injection, the Vi polysaccharide is slowly absorbed from the injection site. Data on its metabolism and elimination are limited.
- Mode of Action: The vaccine’s mode of action centers on its interaction with B cells and T-helper cells within the immune system. The Vi polysaccharide, being a T-independent antigen, primarily activates B cells directly, leading to antibody production without the need for T-helper cell assistance. This immune response primarily targets the Vi capsular polysaccharide, inhibiting bacterial adherence and enhancing phagocytosis.
- Elimination pathways: Information on the elimination pathways is limited.
Dosage
Standard Dosage
Adults: A single 0.5 mL dose intramuscularly (IM) administered in the deltoid muscle.
Children (≥2 years of age): A single 0.5 mL dose intramuscularly (IM) administered in the deltoid or the vastus lateralis muscle.
Special Cases:
- Elderly Patients: The standard adult dosage is generally appropriate.
- Patients with Renal Impairment: Dosage adjustments are not typically necessary.
- Patients with Hepatic Dysfunction: Dosage adjustments are not typically necessary.
- Patients with Comorbid Conditions: No specific dosage adjustments are required, but clinical judgment based on the patient’s overall condition is advised.
Clinical Use Cases
The vaccine is not indicated for use in specific clinical settings like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations. It is used for pre-exposure prophylaxis against typhoid.
Dosage Adjustments
No specific dosage adjustments are typically necessary based on renal or hepatic dysfunction, metabolic disorders, or genetic polymorphisms.
Side Effects
Common Side Effects
- Local reactions at the injection site (pain, redness, swelling).
- Headache.
- Fever.
- Malaise.
Rare but Serious Side Effects
- Allergic reactions (anaphylaxis).
Long-Term Effects
No significant long-term adverse effects have been reported.
Adverse Drug Reactions (ADR)
Clinically significant ADRs are rare but may include severe allergic reactions.
Contraindications
- Severe hypersensitivity reactions to any vaccine component.
- History of life-threatening reaction to a previous dose.
Drug Interactions
No clinically significant drug interactions have been reported.
Pregnancy and Breastfeeding
Information regarding use in pregnancy and lactation is limited. Consult with a healthcare professional.
Drug Profile Summary
- Mechanism of Action: Stimulates the production of antibodies against the S. Typhi Vi capsular polysaccharide.
- Side Effects: Local reactions at the injection site, headache, fever, malaise. Rarely, allergic reactions.
- Contraindications: Hypersensitivity to any vaccine component, history of a life-threatening reaction.
- Drug Interactions: No clinically significant interactions known.
- Pregnancy & Breastfeeding: Limited data; consult a physician.
- Dosage: 0.5 mL IM single dose for adults and children ≥2 years.
- Monitoring Parameters: Monitor for any allergic reactions.
Popular Combinations
No specific drug combinations are routinely recommended. The vaccine can be co-administered with other vaccines.
Precautions
- General Precautions: Screen for contraindications before administration.
- Specific Populations: Assess the benefit-risk ratio for pregnant and breastfeeding women. Standard dosing in children ≥2 years and elderly patients. No specific precautions for menstruating individuals.
- Lifestyle Considerations: No specific lifestyle considerations.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Salmonella Typhi Vaccine?
A: A single 0.5 mL dose intramuscularly for both adults and children ≥2 years of age.
Q2: How often is the typhoid vaccine required?
A: Revaccination is recommended every three years for individuals with continued or repeated exposure to S. Typhi.
Q3: Can the typhoid vaccine be administered with other vaccines?
A: Yes, it can be administered concurrently with other vaccines.
Q4: What is the age range for Typhim Vi administration?
A: It is approved for use in individuals 2 years of age and older.
Q5: What are the common side effects of the typhoid vaccine?
A: Common side effects include injection site reactions (pain, redness, swelling), headache, fever, and malaise.
Q6: Can pregnant or breastfeeding women receive the typhoid vaccine?
A: Consult with a healthcare professional regarding the use of the typhoid vaccine during pregnancy and breastfeeding, as data is limited.
Q7: What should I do if I miss a scheduled dose of the oral typhoid vaccine (Vivotif)?
A: Vivotif is a different formulation (oral) than Typhim Vi. For Typhim Vi, it’s a single dose, so missing a dose isn’t an issue in the same way. If a booster dose is missed, consult a healthcare professional for guidance.
Q8: How effective is the typhoid vaccine?
A: The efficacy of Typhim Vi varies but is generally considered to provide good protection against typhoid fever.
Q9: Is the typhoid vaccine a live vaccine?
A: No, Typhim Vi is not a live vaccine. It contains the purified Vi capsular polysaccharide.
