Viral respiratory diseases may be characterized by rapid diffusion in population, that often cause epidemic outbreaks or pandemic. Besides, typical high mutations of involved virus (almost always influenza virus) can reduce the validity of the up to date available vaccine. The achievement of new vaccines can require prolonged period. In addition, the availability and efficacy of antiviral drugs against new viruses should be evaluated before their uses. Influenza virus replication occurs in the epithelial cells of the respiratory system, and viruses, present in contaminated secretions, spread mainly by aerosols generated during sneezing, coughing, and speaking. Direct and indirect contacts with contaminated fomites play a role, in transmission of viral infection, even if they are less relevant than aerosol transmission. In the absence of ready for use vaccines and active drugs, some "non-pharmaceutical" strategies can be considered decisive factors to reduce the diffusion of pandemic influenza. Hand washing and disinfection procedures, isolation of ill persons, different indication for use of surgical masks and respiratory masks have to be carefully considered.