Available vaccines

Typhoid vaccination is available on the NHS.

• The Vi polysaccharide vaccine, egTypherix®, Typhim Vi®:
  • Composed of purified polysaccharide from S. typhi capsule.
  • Administered subcutaneously or intramuscularly as one dose.
  • Children aged under 2 years respond suboptimally, but the vaccine should be given to children aged between 1-2 years if there is a high risk of infection.
  • It is not recommended for children under 12 months of age.
  • Revaccination (single dose) is recommended every three years.
  • This is also available as a combined vaccination with hepatitis A.
• The Ty21a vaccine, eg Vivotif®:
  • A live attenuated strain of S. typhi and it is an oral vaccine.
  • When administered as three doses on alternate days, immunity is achieved seven days after the last dose.
  • A repeat, full three-dose course is recommended every year in endemic areas.
  • It 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 five years after vaccination in a population of Chilean schoolchildren aged 5-19 years.^[2]
• Inactivated whole-cell vaccine:
  • This has been largely superseded in the UK, but is still available in developing countries.
  • A parenteral vaccine of two doses, four weeks apart.
  • There are efficacy rates of 51-67%, but a high percentage of recipients have fever and systemic reactions with this type.^[2]

Indications for S. typhi vaccination

• Travellers to areas where typhoid is endemic, especially those visiting or staying with local people.
• Travellers to endemic areas, especially where frequent or prolonged exposure to poor sanitation and food hygiene is likely.
• Laboratory personnel whose work may expose them to S. typhi.

Vaccine schedule

• A single dose of inactivated vaccine should be given two weeks before travel, to allow protection to develop fully.
• It can be administered with other inactive vaccines - eg tetanus, poliomyelitis, hepatitis A, meningococcal meningitis, rabies, Japanese B encephalitis and tick-borne encephalitis. It may also be administered at the same time as live vaccines.
• They should be given with separate syringes at separate sites.
• The date, title and batch number should be recorded in the recipient's notes. If more than one vaccine is given, the sites of each should also be recorded.
• Booster doses are required after 3 years. The combined vaccine requires booster Hepatitis A after 6-12 months, but can be given up to 36 months later.
• Children aged less than 2 years have suboptimal response to the vaccine.^[3]
• Typhoid vaccine is not 100% effective. This is particularly so if exposed to large doses of S. typhi. Attention should be paid to personal, food and water hygiene at all times.

Interactions

The oral vaccine Vivotif® is inactivated when antibacterials and some antimalarials are taken at the same time.

• Antibacterials should not be taken for the three-day period before and the three-day period following oral vaccination.
• Mefloquine: the oral vaccination should ideally be completed at least three days before the first dose of mefloquine. If this is not possible, mefloquine should be avoided for at least twelve hours before or after oral typhoid.
• Other antimalarials: oral typhoid vaccination Vivotif® should be completed at least three days before the first dose of the antimalarial.
• Atovaquone with proguanil may be given concomitantly with oral typhoid vaccine Vivotif®.

Contra-indications to vaccine

• HIV-positive individuals should not receive the oral typhoid vaccine Vivotif®.
• Anaphylaxis:
  • The vaccine 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]
  • This also applies if there has been confirmed reaction to a constituent of the vaccine; both combined and single typhoid vaccines contain traces of neomycin.
  • Oral typhoid vaccination Vivotif® is contra-indicated in acute gastrointestinal illness.
• 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° or higher, within 48 hours of the injection.

The following DO NOT contra-indicate vaccination:

• A personal or family history of asthma, allergy, hay fever or eczema.
• Febrile convulsions - advice regarding post-immunisation pyrexia should be given before immunisation.
• Prematurity.
• Stable neurological conditions, eg cerebral palsy, Down's syndrome or epilepsy.
• Contact with infectious disease.
• Treatment with antibiotics or local corticosteroids.
• A child being breast-fed.
• Being underweight.
• Taking replacement corticosteroids.

Special circumstances

• Acute illness - postpone immunisation until recovered.^[3] Minor infections, without fever or systemic upset, are not reasons to postpone.
• Pregnancy - the oral vaccine should be avoided, but termination of pregnancy following inadvertent use is not recommended. There is no evidence of risk from the injectable (inactivated) vaccine.
• Immunosuppression - oral typhoid vaccination should be postponed until at least three months after stopping high-dose systemic corticosteroids, six months after stopping other immunosuppressant drugs or generalised radiotherapy, and twelve months following bone marrow transplantation.
• Evolving neurological problems (eg poorly controlled epilepsy or neurological problems with no known cause) - immunisation should be avoided until the condition is stable.

General advice

• Patients visiting friends and relatives (VFRs) in India, Pakistan and Bangladesh are least likely to attend General Practice for vaccination before travel. They may benefit from targeted opportunistic health promotion strategies informing them of vaccination and hygiene practices while abroad.^[4]
• Reassure patients that the overall risk of contracting infectious diseases from abroad is very low if sensible precautions are taken.^[5]
• Risk of infection varies according to region visited, length of stay and time of year of travel
• 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, eg travellers' diarrhoea, malaria and sexually transmitted disease. Other sensible precautions are also necessary.