The emergence of novel respiratory viruses has often been accompanied by
the disappearance of existing circulating strains. In this chapter, the impact of
pandemics on the circulation of seasonal respiratory viruses is discussed. Some issues
arising from the spread of pandemic viruses and underlying the choices of a strategy of
fighting COVID-19 are under debate.
Keywords: COVID-19, Epidemics, Influenza, Pandemics, Viral respiratory
infections.
