Original article published in: Macau Médico, 1997;1:64-82

Last update: 2009

Content

1. Summary

2. Inroduction

3. Vaccination of the traveler

4. Contraindications to vaccination

5. Vaccine preventable diseases and travel immunobiologicals

6. Bibliography

Summary

Introduction

Travel can be associated to exposures that wouldn’t be expected in the person’s usual environment. Either individually or in group, together with people there are also vectors and organisms that may travel in the same environment, originating or spreading diseases throughout countries, regions or continents – Figure 1.

Figure 1.  The possible travelers

Prevention is the best way to avoid the spread of disease, but will render inefficacious or inefficient if the possible risks of traveling are not assessed – risk management. An effective communication is also very important, because the traveler should understand what we are willing to tell him, and advises should be individually tailored – Figure 2.

Figure 2.  Management of the traveler

Is not easy to get a clear overall picture of the travel-associated health problems. However, there is no doubt that diarrhea due to foodborne and waterborne diseases, usually related to poor hygiene standards and practices, accounts for most of the health problems experienced during travel. This is particularly important in developing countries, which are the most demanded places for travel and holidays. Vaccine preventable diseases account for less than 0.5% of the overall picture.

Vaccination of the Traveler

Doctors should never prescribe specific vaccines for travelers when there is no risk of exposure at the destination. The benefit of avoiding a disease through vaccination must clearly exceed the risk of vaccine adverse events, namely the risk of occasional fatal adverse events. In this case the benefit will be null and the costs extremely high.

In travel medicine, vaccination is not cost saving, but some vaccines may well be worth the additional costs to the overall travel expenses. Obviously, neither doctors nor travelers can demand from their governments that compulsory or recommended vaccines for travel to be included in the local vaccination programs.

However, before prescribing a vaccine, doctors should weight the morbidity aspects of a specific vaccine and it costs, balancing them with the morbidity and prevalence of the disease that the vaccine is intended to prevent – Figure 3.

Figure 3.  Risk management – traveler’s vaccination

There are neither standard drug regimens nor rigid vaccination plans. "Each case should be considered as one specific case" and every prescription should be based on the individual characteristics and the traveler destinations. Whenever necessary, a vaccination plan should be established in time, always considering the traveler’s age, health and immune status, his destination and duration of stay, as well as the time available before departure. This aspect is of paramount importance because no vaccine is able to protect immediately (few days) after its administration.

Some countries may require a proof of vaccination against yellow fever, often after transiting endemic countries, or meningoccocal meningitis, as in Saudi Arabia during the pilgrimage period (Hajj to Mecca in March-April). Any country no longer requires proof of vaccination against smallpox, because the disease is already eradicated (the last naturally occurring case occurred in 1978), neither cholera vaccination, since its efficacy is controversial or null, as for the case of strain Bengal O139.

Contraindications to Vaccination

Before introducing the main aspects of different vaccines that may be prescribed to travelers, doctors should always remember that contraindications to vaccination are very rare. In fact, many considered contraindications have no scientific basis or are false – Table 1.

Table 1.  False contraindications to vaccination

Vaccine combinations (few exceptions), antibiotics, low-dose steroids (less than 20mg per day), minor infections with low fever (below 38.5º Celsius), diarrhea, malnutrition, kidney or liver disease, heart or lung disease, non-progressive encephalopathy, well controlled epilepsy or advanced age, are not contraindications to vaccination. Contrary to what the majority of doctors may think, vaccines against hepatitis B, diphtheria, tetanus and rabies can be applied in any period of the pregnancy.

The only contraindication to most vaccines is the previous hypersensitivity to one of the components, and this mainly applies to inactivated vaccines, like the parenterally administered vaccines against whooping cough (pertussis), tetanus, diphtheria, poliomyelitis, meningitis, hepatitis A, hepatitis B and typhoid.

Formal contraindications. Are linked to states that make vaccination dangerous. These contraindications only apply to live attenuated vaccines, bacterial (Bacillus Calmette-Guérin – BCG) or viral (oral polio, measles, mumps, rubella, yellow fever and oral typhoid), and include:

congenital immune deficiencies, like agammaglobulinaemia,

acquired immune deficiencies, temporary or permanent, like systemic steroid therapy (more than 20mg per day), anticancer therapy and AIDS.

Relative contraindications. Are temporary, often related to vaccine inefficacy and not to the "danger of vaccines". Relative contraindications include:

recent gamma globulin injection (vaccination must be done 6 weeks later),

acute febrile infection (over 38.5º Celsius),

acute cutaneous or respiratory allergy.

Even with lack of scientific evidence, pregnancy may be considered a contraindication to "live vaccines". However, doctors should always bear in mind that the benefit of vaccinating pregnant women usually outweighs potential risks, mainly when the vaccine is unlike to cause harm, the risk of exposure is high or the infection may pose risks to the mother or fetus.

Vaccine Preventable Diseases and Travel Immunobiologicals

Vaccine preventable diseases (VPD) may be transmitted directly or indirectly to man, and some of them may present multiple ways of transmission (like plague). The most common ways of their transmission are summarized in Figure 4.

Vaccinations against meningococcal and pneumococcal diseases, haemophilus influenza b, hepatitis B, poliomyelitis, whooping cough, diphtheria, tetanus, measles, mumps and rubella are routinely administered in childhood, in many countries. Routine vaccination against tetanus may include all age groups. However, whether or not a travel plan exists, considering the local and regional epidemiological situation of VPD, if adults do not have a history of vaccination against these diseases, adequate vaccines for their age and immunization history should be prescribed.

Figure 4.  Transmission of vaccine preventable diseases

In terms of international travel, vaccines can be roughly divided in:

recommended, mainly for persons from low endemicity areas who travel to intermediate or highly endemic regions, and may me related with antigens recommended or included in local vaccination programs (e.g. diphteria, hepatitis B, influenza, measles, mumps, pertussis, pneumococcal disease, poliomyelitis, rubella, tetanus, varicella),

advisable, for selective travellers according to risk of exposure to VPD, namely extended or frequent travel, stay in rural areas, intimate contact with local populations or seasonal risk (e.g. hepatitis A, japanese encephalitis, rabies, tick-borne encephalitis, typhoid fever), and

compulsory, when the proof of vaccination is mandatory for entry in certain countries (e.g. yellow fever or meningococcal disease).

Vaccines for travel according to the geographical areas: (click on desired geographical area)

This section deals with some relevant aspects of immunobiologics that might be prescribed for international travel. However some of them may not be available or supplied free of charge in some countries. The clinical aspects of VPD are not intended to be considered here.

Vaccine preventable diseases and travel medicine immunobiologicals: (click on desired disease/infection)

Recommended  Bibliography

American Committee on Tropical Medicine and Traveler’s Health of the American Society of Tropical Medicine and Hygiene (ASTMH). Health hints for the tropics. 13th edition. ASTMH, 2005.

American Public Health Association (APHA). Control of communicable diseases manual. Heyman DL ed., 18th edition. Washington DC: APHA, 2004.

American Academy of Pediatrics (AAP). Report of the committee on infectious diseases. Pickering LK ed., 26th edition. Elk Grove Village: AAP, 2003.

Australian Government Department of Health and Ageing. The Australian immunisation handbook. 9th edition, 2008.(Available for download at AG-NHMRC site)

Caumes E. Health and travel. Lyon: Pasteur Mérieux, 1999.

Centers for Disease Control and Prevention. Epidemiology and prevention of vaccine-preventable diseases. 10th edition. Washington DC: Public Health Foundation, 2008. (Available for download at CDC site)

Centers for Disease Control and Prevention. General recommendations on immunization: recommendations of the advisory committee on immunization practices. MMWR, 2006;55(RR15). (Available for download at CDC site)

Centers for Disease Control and Prevention. Health information for international travel 2008. Atlanta: US Department of Health and Human Services, 2007. (Online edition at CDC site)

Centers for Disease Control and Prevention (CDC). Manual for the surveillance of vaccine-preventable diseases. 4th edition. Atlanta: CDC, 2008. (Available for download at CDC site)

Centers for Disease Control and Prevention. Update: vaccine side effects, adverse reactions, contraindications, and precautions. MMWR, 1996;45(RR12). (Available for download at CDC site)

Serviços de Saúde de Macau. Programa de vacinação de Macau: normas de vacinação e orientações técnicas. Orientações Técnicas nº 2. Macau: Unidade Técnica de Vigilância Epidemiológica, 1997.

Picazo JJ. Guia práctica de vacunaciones 2002. Madrid: Fundación para el Estudio de la Infección, 2002. (Online edition at vacunas.net)

Plotkin AS, Orenstein WA. Vaccines. 4th edition. Philadelphia: WB Saunders Company, 2004.

World Health Organization. Immunization policy. WHO, Global Programme for Vaccines and Immunization, Expanded Programme on Immunization, Geneva, WHO/EPI/GEN95.3, 1995.

World Health Organization (WHO). International travel and health 2008. Geneva: WHO, 2008. (Online edition at WHO site)

 © Fernando Costa Silva, 1999 (last update: 2009)