typhoid vaccine: clinical use

Prescribing considerations

• Assess destination or exposure risk and reinforce food, water and personal hygiene because protection is incomplete.
• Review previous immunisations, vaccine reactions, current health, allergies, immune status and bleeding risk.
• Postpone vaccination during acute or febrile illness; a minor illness without fever or systemic upset is not usually a reason to defer.
• Vi vaccine is non-live and may be used in immunosuppressed people, but the immune response can be reduced.
• Record the product name and batch number for traceability.

Contraindications and cautions

• Hypersensitivity to the active substance, excipients or residual formaldehyde or casein.
• Previous confirmed anaphylaxis to a Vi antigen-containing vaccine.
• Acute or febrile illness requires postponement rather than permanent exclusion.

Monitoring

• Ensure facilities and trained staff are available to recognise and treat anaphylaxis.
• Use procedures that reduce injury from vaccination-related fainting.
• Observe clinically for immediate allergy or syncope and advise about expected local and systemic reactions.
• No routine pharmacokinetic or serum-level monitoring applies.

Clinical pharmacology

Purified Salmonella Typhi Vi capsular polysaccharide induces a humoral anti-Vi immune response. Immunogenicity may be reduced by immunodeficiency or immunosuppressive treatment, and protection is not universal.

Formulation and product differences

• The selected product is a clear, colourless, non-live solution supplied in a pre-filled syringe.
• Needle presentations vary; some presentations include an attached needle or separate needles.
• It contains phenol as a preservative and a saline-phosphate buffer and is essentially sodium-free.
• Unlike oral typhoid vaccine, it contains no live attenuated organism; combined hepatitis A and typhoid vaccines are separate products.
• Store refrigerated, protect from light and do not freeze; inspect and shake before administration.