Vaccines for International Travel

Simultaneous Administration of Vaccines and Immunoglobulin

Scheduling multiple vaccines for the traveler can be challenging, especially when departures are imminent. Although scheduling a consultation at least 4–6 weeks before travel is ideal, few travelers allow as long as a month, and many come for consultation only a few days before departure. Whenever the traveler is seen, there is potential for helpful information to be given, and some agents (e.g., hepatitis A vaccine, influenza vaccine when available, updates on routine vaccines), can be given with good effectiveness even on the day of departure. Immunization schedules can be accelerated, or vaccines limited to those most appropriate to the infectious disease risks likely to be faced by the traveler. Although many patients and providers are concerned about the likelihood of adverse reactions to multiple vaccines administered simultaneously, studies performed in travel clinics that evaluated simultaneous administration of multiple vaccines, including travel vaccines, reported that adverse events were generally minor and not incapacitating. ^, The ACIP encourages simultaneous administration of all needed vaccines.

Non-live vaccines can be given concurrently or at any interval before or after other non-live or live vaccines (see Chapter 10 ). https://www.cdc.gov/vaccines/covid-19/hcp/faq.html . Live vaccines [such as yellow fever, measles–mumps–rubella (MMR), and varicella] should be administered either simultaneously or at least 28 days apart. When live vaccines are given less than 28 days apart, the second should not be counted as valid and should be repeated at least 28 days from the first administration. Some data exist to support exceptions: oral poliovirus vaccine (OPV), no longer used in many countries, may be given at any interval before or after parenteral live vaccines; yellow fever vaccine may be given at any interval with respect to monovalent measles vaccine; and Ty21a oral typhoid vaccine may be given at the same time as or at any interval relative to parenteral live vaccines (MMR, varicella, yellow fever). ^,

Antibody responses to MMR and varicella vaccines may be impaired if given at the same time as immunoglobulin. MMR and varicella vaccines should be administered at least 2 weeks before immunoglobulin, although they can be administered at the same time, if necessary. If immunoglobulin is given before MMR or varicella vaccines, the appropriate time interval after immunoglobulin for giving these vaccines depends on the dose of immunoglobulin administered; a helpful table detailing appropriate intervals is available. Immunoglobulin has not been shown to interfere with responses to polio, yellow fever, or oral typhoid vaccines.

Immunization of Persons With Altered Immunocompetence

Detailed recommendations regarding immunization of immunocompromised persons are published elsewhere (see Chapter 70 ) and are available from the CDC and from the Infectious Diseases Society of America. ^, Information specific to immunocompromised travelers is available from the CDC. In general, immunocompromised persons should not receive live viral vaccines, but there may be some exceptions. Information specific to travel vaccines is presented in the sections on individual vaccines below.

Effect of Antimalarials and Antimicrobial Agents on Vaccine Response

When antimalarials in the chloroquine/mefloquine family are administered simultaneously with human diploid cell rabies vaccines, they may interfere with immunogenicity of the vaccines. It does not appear that these antimalarials interfere with immunogenicity of the oral typhoid vaccine. The combination of antimicrobial agents and oral typhoid or cholera vaccines is contraindicated because they would probably interfere with the activity of these live bacterial vaccines. Details of these interactions can be found in the sections devoted to individual vaccines below.

Routine Immunizations and Modifications Needed for Travelers

Routine childhood and adult immunizations should be brought up to date as part of the preparation for international travel. Information is available from many sources about routine immunizations; many countries update their immunization plan every year. In the United States, schedules are available from the CDC on the Internet ( https://www.cdc.gov/vaccines/acip/recommendations.html ). Readers are also referred to country-specific schedules for this information. Some travelers will require accelerated schedules because of imminent departure dates or because of immunization delays. The reader is referred to Chapter 10 and Chapter 74 for routine and accelerated schedules in the United States and to the chapters on individual vaccines for detailed information. Children in the United States are immunized routinely against 16 diseases ( Table 71.1 ). Most diseases for which children are immunized routinely are present worldwide, although the risk of contracting them varies markedly depending on the travel destination. Additional information about adult immunization is available. Indications specific to travel are given in sections referring to individual vaccines below. All adults should be up to date with routine childhood immunizations, and all (who have no contraindication) in the United States should receive annual influenza vaccination; influenza immunization is recommended from age 60 or 65 years in some countries, although the risk of influenza is worldwide. Those 65 years of age or older, or at any age with certain medical conditions, should be immunized against pneumococcal disease. Older adults without contraindications should be considered for zoster vaccine; the age at which it is given varies by country (e.g., 50s in the United States, 70s in the UK, etc.).