Rhino- and RS-viruses in the COVID-19 pandemic

Abstract

Acute respiratory viral infections are distributed across the globe and are the most numerous human diseases caused by several hundreds of diverse viruses. Human rhinovirus is one of the most common respiratory pathogens worldwide, causing more than half of all acute respiratory viral infection cases. Seasonal human coronaviruses account for 1015% of common cold cases; respiratory syncytial (RS) virus is the most common cause of respiratory hospitalization in infants; influenza viruses, adenoviruses, human parainfluenza virus, metapneumoviruses, and some other pathogens are also widespread. It is believed that viral common colds are mostly self-limited, causing mild infections that usually resolve within 810 days. However, the role of common seasonal respiratory viruses in total respiratory morbidity should not be underestimated. It turned out that during extraordinary conditions of pandemics, they behave differently. This was clearly demonstrated in the last 2009 influenza pandemic. Whereas some viruses lost relevance under the burden of a new aggressive pandemic strain, others, e.g., rhinovirus, continued to fight for existence and not only circulated along with the pandemic pathogen, but delayed its spread in some cases. For instance, the data from some European countries pointed out that the circulation of the H1N1pdm09 influenza A pandemic virus was interrupted by the annual rhinovirus outbreak. Ten years after the H1N1pdm09 influenza pandemic, a new virus outbreak emerged the COVID-19 pandemic has begun. This pandemic, caused by the SARS-CoV-2 virus, has disrupted well-established pathogenetic and epidemiological relationships. The level of circulation of many respiratory pathogens has changed dramatically. For instance, global influenza activity has been at a much lower level than expected for the second year from now. In many regions of the world, the flu season has not been started yet. But what is interesting is that rhinoviruses together with RS-virus again showed their unique ability to compete with highly pathogenic and aggressive pathogens. Along with profoundly reduced circulation of many other seasonal respiratory viruses, rhinovirus, and RS-virus are the most frequently detected viruses. In this review, we have brought together the main biological characteristics of such genetically distinct viruses such as rhinovirus, influenza A virus, RS-virus, and SARS-CoV-2. We focused on their main similarities and discrepancies in the attempt to understand why they behave so differently in extreme pandemic conditions as well as what allows rhinoviruses and RS-viruses to coexist with SARS-CoV-2, which in turn almost fully replaced the influenza virus.