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Best travel health advice: the A-Z of vaccinations

Jane Zuckerman
MD FRCPath FFPM FIBiol
Director of the Academic Centre for Reference, Research and Training in Travel Medicine
Director of the WHO Collaborating Centre for Travel Medicine at the Royal Free & University College Medical School
T:020 7830 2999
F:020 7830 2268
E:j.zuckerman@rfc.ucl.ac.uk

Travellers may be exposed to a variety of infectious diseases, and it is essential to undertake a travel health risk assessment to determine the risk of exposure and subsequently to advise about methods of prevention.(1) A significant number of infectious diseases to which travellers may be exposed are considered to be vaccine-preventable.(2,3)

Routine travel immunisations
Immunisations considered more routinely for travellers, but depending upon their destination and purpose of travel, include poliomyelitis, tetanus/diphtheria, hepatitis A and typhoid.

Poliomyelitis
Although routine childhood immunisation programmes exist in developed countries, travellers from such countries may remain at risk of infection with poliomyelitis because they have never received a course of immunisation, in particular older travellers, because a booster dose has not been administered or because the disease remains endemic in some developing countries being visited. It would therefore seem prudent for those travellers at particular risk to maintain levels of protection against poliomyelitis and receive booster doses of polio vaccine every 10 years.

Tetanus/diphtheria
An adult born before 1940 who has never received either diphtheria or tetanus vaccine and is travelling to an epidemic/endemic area should be immunised with three doses of tetanus/low-dose diphtheria (Td) vaccine, given one month apart. Guidance from the Department of Health (DH) now advises that single- antigen tetanus vaccine should be replaced by the combined Td vaccine for previously unimmunised adults and adolescents. This decision was implemented in order to maintain the levels of herd immunity within the UK. In some settings, travellers may find themselves exposed to a risk of infection with tetanus as a result of an injury, and so booster doses of Td should also be administered where a booster dose of tetanus is indicated because of travel, and when more than 10 years has elapsed since the last booster dose. Single- antigen low-dose diphtheria may still be used where its use is indicated and the traveller is fully protected against tetanus.(4)

Hepatitis A
Hepatitis A vaccine is an inactivated vaccine that may be administered as a monovalent or multivalent vaccine. As a monovalent vaccine, hepatitis A is administered intramuscularly as a two-dose schedule, with the primary dose being administered at day 0 and a booster dose 6-12 months later. Immunity is conferred to 98% of vaccinees within 7-10 days of administration of the first dose of hepatitis A vaccine, with the booster dose given at 6-12 months giving long-term protection for up to 20 years. Hepatitis A vaccine is licensed for use in children between 1 and 15 years as a 0.5ml dose, and its administration is to be encouraged in children when they travel to reduce the importation of disease and subsequent public health implications. Studies have demonstrated that the booster dose may be administered up to 3-5 years after the primary dose, which elicits an excellent immune memory response.(5) Another recent study demonstrated that rapid levels of protection are obtained within 12 days of vaccination with hepatitis A, so confirming the administration of this vaccine for those who travel at short notice.(6) A recent report has shown that, after a full primary vaccination course, protective hepatitis A antibody persists beyond 10 years. These findings do suggest that it is unnecessary to routinely administer booster doses of hepatitis A vaccine following completion of the primary course in healthy individuals.(7)

Typhoid
Typhoid vaccine is recommended for those travelling to Africa, the Indian subcontinent, Central and South America and in countries where hygiene and sanitation are poor, as in some Eastern European countries. A booster is required every 3 years for those at repeated risk. Typhoid vaccine is available both as an inactivated polysaccharide vaccine, which is much less reactogenic than previous formulations, and as an oral live vaccine formulation, where the primary course is administered as one capsule taken on three alternate days and requires the complete course to be administered as a booster at three-yearly intervals.

Multivalent vaccines
Combination vaccines such as hepatitis A and typhoid, and hepatitis A and B, provide dual protection by a single injection for diseases whose epidemiological profiles are similar and also increase compliance and convenience, particularly for those with a fear of needles.
Such vaccines also have another advantage in making another site of injection available when time is short and multiple immunisations need to be considered. Hepatitis A/typhoid, an inactivated vaccine, is administered as a single-dose primary course for adults and adolescents of 15 years of age and over and provides protection against hepatitis A for 1 year and typhoid for 3 years.
The administration of a booster dose of the monovalent hepatitis A vaccine, 6-12 months following the primary dose, will provide immunity for at least 10 years against hepatitis A.

Optional travel vaccines to be considered
Optional vaccines to be considered include Japanese encephalitis, recommended for travellers visiting rural areas of South East Asia and the Far East for longer than a month, and tick-borne encephalitis, another insect-borne disease causing meningoencephalitis.  Japanese encephalitis may be administered according to the following schedules:

  • Day 0, 7 and 30 days.
  • Day 0, 7 and 14 days.
  • Day 0 and 7 days, which provides protection in approximately 80% of vaccinees.

Japanese encephalitis is a reactogenic vaccine with an incidence rate of severe reactions occurring following administration of 5-10 per 10,000 doses and within 2 weeks of the vaccination. Adverse reactions include urticaria and angioedema; vaccination is therefore recommended at least 2 weeks before travel.
Tick-borne encephalitis is endemic in forested areas of Central and Eastern Europe and Scandinavia and is recommended for those camping, walking or working forested areas during late spring and summer. The schedule of vaccination is two doses administered 1-3 months apart, with the third dose being administered 9-12 months later. Japanese encephalitis vaccine is unlicensed and available only on a named-patient basis.
Rabies vaccine is recommended for those travelling in enzootic areas or who may be far from medical help and is administered at day 0, 7 and 28 with a booster every 3-5 years according to the risk of exposure. An alternative schedule is day 0 and 28, which should be used in exceptional circumstances as it may be considered as incomplete pre-exposure protection in other countries. Intradermal immunisation should not be used in those taking chloroquine, as suppression of the immune response to the vaccine may occur.
Hepatitis B vaccine is advised for those travelling to areas of high endemicity - that is, outside Northwestern Europe, North America, Australia and New Zealand. As a blood-borne and sexually transmitted virus, travellers may be exposed by virtue of their sexual behaviour, by the use of unscreened blood or blood products or inadequately sterilised medical and surgical equipment that may be required following an accident or illness while abroad.(8) Rapid schedules of administration of vaccines include that of the monovalent hepatitis B vaccine, which can now be administered according to three different schedules as follows:

  • Day 0, 1 and 6 months.
  • Day 0, 1 and 2 months with a booster at 12 months.
  • Day 0, 7 and 21 days with a booster at 12 months.

More recently, a two-dose schedule of hepatitis B vaccine has been licensed for children between 10 and 15 years of age where low compliance with completion of the other schedules is anticipated. In this case, a 1ml dose is administered at day 0, 1 or 6 months.(9)
The bivalent hepatitis A and B vaccine may be administered according to two schedules as follows:

  • A 1ml dose for adults (0.5ml for children between 1 and 15 years) at day 0, 1 and 6 months.
  • As a rapid schedule at day 0, 7 and 21 days with a booster at 12 months for those at high risk. This is licensed for adults of 18 years of age and over.

Both schedules provide protection for 5 years against hepatitis B and at least 10 years for hepatitis A, similar profiles to those of the monovalent vaccines.  Administration of booster doses using the monovalent vaccines may be considered, where appropriate.

Mandatory vaccines
Mandatory vaccines for which certification is often necessary include yellow fever and meningoccocal meningitis as appropriate to the destination. Yellow fever vaccine, a live vaccine, is recommended for those travelling to countries in Sub-Saharan Africa and South America and is mandatory for those travellers arriving from infected areas.  Immunisation must be documented by an International Certificate of Vaccination, which is valid for 10 years from 10 days after vaccination.
Other more uncommon vaccines may be need to be considered, including that of meningoccocal meningitis ACWY, particularly for aid workers and those travellers who will be in close contact with the indigenous population.(9) Vaccination against meningococcal meningitis is mandatory for those travelling for the Hajj and Umra, and a certificate of vaccination is required by the authorities. Recent guidance has recommended that the quadrivalent meningococcal meningitis vaccine is the vaccine of choice for all travellers at risk of Neiserria meningitides due to the increasing prevalence of the W135 strain throughout the African continent. As a consequence, meningococcal meningitis A & C is being withdrawn.
High-risk travellers would benefit from the administration of vaccines such as influenza, whose seasonal prevalence differs in temperate and tropical climates, pneumococcal vaccine as well as hepatitis B vaccine.

Conclusion
The importance of addressing the health needs of travellers cannot be emphasised enough in terms of both the individual and the potential public health implications.(10) This can be achieved by completing a thorough travel health risk assessment and the use of the appropriate safe and highly immunogenic vaccines to protect against travel-related infectious diseases.

References

  1. Stringer C, Chiodini J, Zuckerman JN. Travel health risk assessment. Nurs Stand 2002;16(39):49-54.
  2. World Health Organization. International Travel and Health, Vaccination Requirements and Health Advice. WHO; 2001.
  3. Zuckerman JN. Vaccine-­preventable disease. In: Zuckerman JN, editor. Principles & practice of travel medicine. Chichester: John Wiley and Sons; 2001.
  4. Replacement of single antigen tetanus vaccine by combined tetanus/low dose diphtheria vaccine for adults and adolescents. London: Department of Health; 2002.
  5. Iwarson S, Lindh M, Widerstrom L. Excellent booster response 4-6 y after a single primary dose of an inactivated hepatitis A vaccine. Scand J Infect Dis 2002;34:110-1.
  6. Van Damme P, Lievens M, Stoffel M, Ngyuyen C. Rapid seroconversion rates after the first dose of an inactivated hepatitis A vaccine (Havrix 1440(TM): results of a retrospective analysis. Poster presented at 3rd European Conference on Travel Medicine, Florence, Italy, May 2002.
  7. Van Damme P, Banatvala J, Fay O, et al. Hepatitis A booster ­vaccination: is there a need? Lancet 2003 Sep 27;362(9389):1065-71.
  8. Zuckerman JN, Steffen R. Risks of hepatitis B in travelers as compared to immunization status. J Trav Med 2000;7:170-4.
  9. Bock HL, Loscher T, Scheiermann N, et al. Accelerated schedule for hepatitis B ­immunization. J Trav Med 1995;2:213-7.
  10. Getting Ahead of the Curve - a strategy for combating infectious diseases in the United Kingdom. London: Department of Health; January 2002.