Typhoid conjugate vaccine

• Prevention of Typhoid Fever:
  Approved for active immunization against Salmonella enterica serotype Typhi, the causative agent of typhoid fever.
• Target Populations:
• Children aged 6 months and older.
• Adolescents and adults at increased risk due to endemic exposure or travel to typhoid-endemic regions.
• Use in Outbreak Control:
  Recommended in typhoid fever outbreak settings to control spread.
• Important Off-label/Clinical Uses:
• Protection in populations with multidrug-resistant (MDR) or extensively drug-resistant (XDR) typhoid strains.
• Use in routine immunization schedules in endemic countries.

• Standard Dose:
• Single dose of 0.5 mL administered intramuscularly (IM).
• Age Groups:
• Approved for children from 6 months to 45 years (varies by product and region).
• Booster Dose:
• Not routinely required within 3 years post-primary vaccination; booster doses may be considered based on epidemiology and risk.
• Administration Route:
• Intramuscular injection, preferably in the deltoid muscle.
• Special Populations:
• Immunocompromised: May receive vaccine; however, immune response may be reduced.
• Pregnant women: Limited data; vaccination only if clearly needed.
• Storage and handling: Ensure cold chain is maintained before administration.

Typhoid Conjugate Vaccines consist of the Vi capsular polysaccharide antigen from Salmonella Typhi covalently linked (conjugated) to a carrier protein such as tetanus toxoid or diphtheria toxoid. This conjugation induces a T-cell dependent immune response, enhancing immunogenicity, especially in young children who do not respond well to polysaccharide antigens alone. Upon administration, the vaccine stimulates the immune system to produce specific anti-Vi antibodies that neutralize Salmonella Typhi bacteria, thereby preventing systemic infection and disease.

Not applicable for vaccines as they act via immune system activation rather than classical ADME processes.

• Pregnancy:
• Classified as Category C or no assigned FDA category.
• Limited human data; generally not recommended during pregnancy unless benefits outweigh risks.
• Lactation:
• No data on excretion in human milk. Vaccination during breastfeeding is generally considered safe.

• Primary class: Vaccine
• Subclass: Conjugate vaccine (polysaccharide-protein conjugate)
• Generation: Next-generation typhoid vaccines with enhanced immunogenicity

• Known hypersensitivity to any component of the vaccine, including carrier proteins.
• Severe acute illness with or without fever (vaccination deferred until recovery).
• Previous severe allergic reaction to a dose of any typhoid vaccine.

• Use with caution in individuals with a history of severe allergic reactions.
• Monitor for immediate hypersensitivity reactions post-vaccination.
• Immunocompromised individuals may have reduced immune response.
• Ensure appropriate resuscitation facilities are available during vaccination sessions.
• Not a substitute for sanitary measures such as safe drinking water and hygiene.

• Common (within 1–7 days):
• Injection site pain, redness, swelling
• Mild fever
• Headache
• Fatigue
• Less common:
• Myalgia, arthralgia
• Gastrointestinal discomfort
• Rare:
• Severe allergic reactions (anaphylaxis)
• Localized lymphadenopathy
• Side effects are typically mild and self-limiting.

• No known significant drug-drug interactions.
• May be administered concomitantly with other routine childhood vaccines at different injection sites.
• Avoid concomitant administration with other live vaccines unless clinically indicated.

• WHO prequalified several TCVs since 2017, endorsing their use in routine immunization programs.
• WHO Strategic Advisory Group of Experts (SAGE) recommends introduction of TCVs in typhoid-endemic countries, prioritizing children from 6 months of age.
• Recent clinical trials show sustained protection up to 3 years post-vaccination.
• Updated guidelines emphasize vaccination as part of integrated typhoid control alongside water and sanitation improvements.

• Store at 2°C to 8°C (refrigerated).
• Protect from freezing; do not freeze.
• Protect from light exposure; store in original packaging until use.
• Maintain cold chain from manufacture to administration site.