[How to manage vaccinations in the elderly traveler]

Along with the growth of travels, the ageing of the population multiplies the number of older travellers. 13% of travellers could be at least 65 years old. It is admitted that there is no upper age limit to perform immunizations. Immunizations are all the more useful for older people because age generally aggravates infectious diseases. With age the immune response decreases definitely, especially that depending on cellular immunity, as well as the humoral response, as it has been observed with vaccinations against tetanus, flu, pneumococcal infections and hepatitis B. The first series of immunizations could be more affected by age than boosters. But a lot of questions still remain unanswered. Is there a maximum age beyond which the immune response would be unadapted to such an extent that it would be necessary to modify the immunization protocols as well as the periodicity of boosters? 75 years? 80 years? Is this age the same for all individuals? Is that a matter of a lower level of the antibody response, or rather of a slower, delayed response? The planning of older travellers immunizations meets another difficulty: their often vague knowledge of past immunization records and infectious diseases. One is often reduced to conjectures. Thus men, who have served in the army since the beginning of World War II are supposed to have got the first series of immunization against tetanus and diphtheria, but how can we restore their immunity (once we have defined the maximum age) when boosters have been either insufficient or missing? Conversely for women born before 1945, who were probably never immunized, a first series of immunization is warranted. On the other hand, since the immunization against poliomyelitis only came into effect in the sixties, most older adults have never been immunized but have acquired in the past a natural immunity from their contact with wild polio viruses. Naturally acquired antipoliovirus immunity doesn't seem to have decreased with age, unlike antidiphtheria and antitetanus immunity, as shown by recent serologic studies. Thus would a single booster with inactivated polio vaccine be sufficient to reinforce the immunity of most older travellers who have never been immunized? Considering these uncertainties, one could think of carrying out a serologic assessment prior to establishing an immunization program, as it has already been recommended for the immunization against hepatitis A. What would its feasibility be? There are quite a lot of questions to discuss. May this round table help define these questions and specify which investigations would be necessary to solve them, as well as program more rationally the immunizations of the older traveller.