Vaccination

Influenza

In the north hemisphere, the flu peak activity occurs between November and March, and in the southern hemisphere between April and September; in the tropics, influenza can occur throughout the year. Its transmission may be enhanced in crowded conditions, including air and cruise travel. The elderly and younger persons with respiratory and cardiac problems, diabetes mellitus and those with any immunodeficiency condition are at most risk of severe disease.

The use of the trivalent inactivated flu vaccine requires an annual adaptation, and should be administered at least one month before the beginning of the flu/cold season (one yearly dose). Travellers belonging to influenza high-risk groups shoud get a yearly vaccination. Those travelling from one hemisphere to the other shortly before the infuenza season should get vaccinated accordingly or, if not possible, arrange vaccination as soon as possible after arrival to the destination.

Adults and children over 9 years of age should receive one dose of flu vaccine (plus one dose every subsequent years). Children 3-9 years od age, and all immunocompromised people, should receive two doses at least four weeks apart, if they are receiving the flu vaccine for the first time (plus one dose every subsequent years); if it´s not the first time, should receive only one dose. Those aged 6-36 months should be vaccinated with half the adult dose, repeated 4-6 weeks later if they receive the vaccine for the first time.

Fernando Costa Silva, 1999 (last update: 2009)