Abstract
Seasonal influenza affects 5-15% of the world's population annually and is considered to be the second most frequent vaccine-preventable infection in travelers. Despite increasing travel volume worldwide, guidelines on influenza vaccination for international travel are scarce. On the basis of some national recommendations, influenza vaccine should be used based on host criteria to usual risk groups, such as old (> 50-65 years) or young (6-23 months) age and those with comorbidities. Additionally, environmental and behavioral factors must be considered. Close contact with high transmission has been documented in cruise ships and during mass gatherings. Travelers crossing to the opposite hemisphere in influenza-peak season may need protection. Those visiting the tropics are at moderate risk of infection and illness during the entire year. A summary on existing traveler recommendations relating to avian influenza is included.