[Influenza]

Influenza outbreaks remain today among the most serious and intractable health problems owing to high rates of morbidity and high economic costs. Periodical epidemics and pandemics in temperate regions of the world are due to high genetic variability of influenza viruses, which concerns primarily haemagglutinin and neuraminidase antigens (antigenic drift and shift). Most influenza infections are self-limited, but they cause increased mortality in high-risk groups of population (such as the elderly and the subjects with chronic diseases) and increased morbidity in the general population, with loss of productivity and high health costs. During the past thirty years, efforts to control influenza have focused on the use of inactivated vaccines in high-risk groups and of two antiviral drugs, amantadine and rimantadine. However, the wide spread of influenza in all population groups and the limits of adamantane compounds induced to investigate novel approaches for prevention and control of flu. The new live attenuated, cold-adapted, trivalent intranasal vaccine was shown to be highly effective in children against influenza A (H3N2) and B viruses. The new antiviral drugs (zanamivir and oseltamivir), neuraminidase inhibitors, reduced the median time to alleviation of the major symptoms of influenza by 1-2 days. These advances in the last few years will certainly modify our approaches to influenza treatment and prevention.