Typhoid Vaccination

• Approximately 200 cases are notified in Britain each year. Most of these are contracted from the Indian subcontinent.
• Typhoid is endemic to areas of poor sanitation e.g. Africa, Asia, Central and Southern America and the Caribbean. Avoiding contaminated water can help in preventing infection, but vaccination is recommended.
• The incubation period is 1-3 weeks.
• Around 10% of people infected can excrete the virus for up to 3 months. Nearly half become permanent carriers.¹

Typhoid vaccination is available on the NHS.

1. The Vi Polysaccharide vaccine. e.g.Typherix™, Typhim Vi™:
   • Composed of purified polysaccharide from S. typhi capsule.
   • Administered subcutaneously or intramuscularly as one dose.
   • It is not effective in individuals under 2 years.
   • Revaccination (single dose) is recommended every 3 years.
   • This is also available as a combined vaccination with Hepatitis A.
2. The Ty21a vaccine. e.g. Vivotif™:
   • A live attenuated strain of S. typhi.
   • When administered as 3 doses on alternate days, immunity is achieved 7 days after the last dose.
   • A repeat, full 3 dose course is recommended every year in endemic areas.
   • Is given as enteric-coated capsules and is licensed from 6 years of age.
   • More immunogenic oral vaccines are being researched currently as protective efficacy of the vaccine can vary.
   • A liquid formulation was shown to have 79% efficacy for up to 5 years after vaccination in a population of Chilean schoolchildren aged 5-19 years.²
3. Inactivated whole cell vaccine:
   • Largely superseded in the UK, but still available in developing countries.
   • A parenteral vaccine of 2 doses, 4 weeks apart.
   • Efficacy rates of 51-67%, but high percentage of recipients have fever and systemic reactions with this type.²

• Anaphylaxis:
  • Should not be given to those who have had a confirmed anaphylactic reaction within 72 hours of a previous dose of the same vaccine.³
  • Also confirmed reaction to a constituent of the vaccine; both combined and single typhoid vaccines contain traces of neomycin.
• Other severe adverse reactions. This means an extensive area of redness and swelling affecting a large area of the arm or leg, accompanied by a fever of 39.5 degrees or higher, within 48 hours of the injection.

The following DO NOT contraindicate vaccination:

• A personal or family history of asthma, allergy, hay fever or eczema
• Prematurity
• Stable neurological conditions e.g. cerebral palsy, Down's syndrome or epilepsy
• Contact with infectious disease
• Treatment with antibiotics or local corticosteroids
• Child is being breast fed or mother is pregnant
• Under weight
• Taking replacement corticosteroids

• Acute illness - Postpone immunisation until recovered.³ Minor infections, without fever or systemic upset are not reasons to postpone.
• Pregnancy - Injectable (inactivated) typhoid is probably safe. The risks to the fetus are likely to be negligible. Use only if there is a clearly indicated risk.
• Immunosuppression or HIV - Inactivated vaccines can be given, regardless of CD4 count. However these individuals may not be able to mount a full immune response. It is recommended that vaccines are delayed, if possible, until the immunosuppressants have finished.

• Reassure patients that the overall risk of contracting infectious diseases from abroad is very low if sensible precautions are taken.⁴
• Risk of infection varies according to region visited, length of stay and time of year of travel
• Type of travel. People are more at risk in rural areas than urban ones.
• Age and general health of the traveller. Some people may be more susceptible to infection.
• The most common infectious diseases cannot be effectively vaccinated against e.g. traveller's diarrhoea, malaria and sexually transmitted disease. Other sensible precautions are also necessary.