Scientists are constantly challenged to identify major newly emerging strains of influenza viruses, so that effective vaccines can be formulated in time. Compared to last year's recommendations for the vaccine, one of the three influenza vaccine components has been changed. Every February, the influenza experts advise the national health authorities and pharmaceutical companies on the composition of the virus strains that should be used to produce vaccines for the next influenza season.
Influenza causes epidemics worldwide every year.
WHO strongly advises the use of vaccine as a sound preventive measure against this potentially fatal disease. Special attention should be paid to vaccinate the elderly, individuals with immunodeficiency, sufferers of chronic diseases of the heart or lungs as well as diabetes. For the adult population one dose of inactivated vaccine should be adequate. However, previously unimmunized children in these categories should receive two doses of vaccine, with an interval between doses of at least four weeks. We believe that up to 80 per cent of recipients will be protected against disease when there is a good match between the vaccine and circulating strains.