Typhoid vaccine (live)

How it works

The attenuated Ty21a strain replicates transiently in the gut to stimulate a protective mucosal and systemic immune response without causing disease.

Prescribing in practice

• As a live vaccine it is contraindicated in significant immunosuppression and in pregnancy unless the risk of typhoid exposure clearly outweighs the theoretical risk.
• The oral capsules must be taken apart from food and swallowed whole with a cool drink, and the full course completed to achieve protection.
• Concurrent antibacterials, antimalarials such as proguanil, and certain other agents can inactivate the vaccine, so administration timing should follow current prescribing references.

Monitoring

No routine laboratory monitoring is required; observe for tolerability and ensure the full schedule is completed and a booster taken at the recommended interval for continued exposure.

Counselling the patient

• Complete the entire course and keep the capsules refrigerated as directed.
• Protection is not absolute, so maintain strict food and water hygiene while travelling.
• Tell the team if you are taking antibiotics or are or might be pregnant before starting.

Evidence & guidelines

Use is supported by UK immunisation guidance (the Green Book) and travel health recommendations for endemic regions.