Circulation Patterns of Seasonal Respiratory Viruses during the COVID-19 Pandemic

When faced with a new virus that is rapidly emerging in the human population, we had a limited knowledge base to work with. The pandemic invasion of the new SARS-CoV-2 virus provided a unique possibility to quickly learn more about the pathogenesis of respiratory viruses. What happens to other respiratory infectious diseases during a global disaster such as the COVID-19 pandemic? The pandemic brought about by the novel SARS-CoV-2 virus has disrupted many well-established epidemiological and pathogenetic relationships, as well as mechanisms affecting infections with other respiratory viruses. Typically, the emergence of novel respiratory viruses has often been accompanied by the disappearance of existing circulating strains. As of today, there is a general downward trend in the circulation of seasonal respiratory viruses with one major exception – rhinovirus and respiratory-syncytial virus – which are not being halted. The level of circulation of other respiratory pathogens has dropped dramatically. In many regions, the influenza season has not started. In this chapter, the impact of pandemics on the circulation of seasonal respiratory viruses is considered. Some issues arising from the spread of pandemic viruses and underlying the choices of a strategy to fight the coronavirus infection are discussed.