It is well known that rhinoviruses are distributed across the globe and are the most common cause of the common cold in all age groups. Rhinoviruses are widely considered to be harmless because they are generally perceived as respiratory viruses only capable of causing mild disease. However, they may also infect the lower respiratory tract, inducing chronic obstructive pulmonary disease and exacerbations of asthma, bronchiolitis, etc. The role of rhinoviruses in pathogenesis and the epidemiological process is underestimated, and they need to be intensively studied. In the light of recent data, it is now known that rhinoviruses could be one of the key epidemiological barriers that may influence the spread of influenza and novel coronaviruses. It has been reported that endemic human rhinoviruses delayed the development of the H1N1pdm09 influenza pandemic through viral interference. Moreover, human rhinoviruses have been suggested to block SARS-CoV-2 replication in the airways by triggering an interferon response. In this review, we summarized the main biological characteristics of genetically distinct viruses such as rhinoviruses, influenza viruses, and SARS-CoV-2 in an attempt to illuminate their main discrepancies and similarities. We hope that this comparative analysis will help us to better understand in which direction research in this area should move.

The COVID-19 pandemic had a profound impact on influenza activity worldwide. However, as the pandemic progressed, influenza activity resumed. Here, we describe the influenza epidemic of high intensity of the 2022–2023 season. The epidemic had an early start and peaked in week 51.2022. The extremely high intensity of the epidemic may have been due to a significant decrease in herd immunity. The results of PCR-testing of 220,067 clinical samples revealed that the influenza A(H1N1)pdm09 virus dominated, causing 56.4% of positive cases, while A(H3N2) influenza subtype accounted for only 0.6%, and influenza B of Victoria lineage—for 34.3%. The influenza vaccine was found to be highly effective, with an estimated effectiveness of 92.7% in preventing admission with laboratory-confirmed influenza severe acute respiratory illness (SARI) cases and 54.7% in preventing influenza-like illness/acute respiratory illness (ILI/ARI) cases due to antigenic matching of circulated viruses with influenza vaccine strains for the season. Full genome next-generation sequencing of 1723 influenza A(H1N1)pdm09 viruses showed that all of them fell within clade 6B.1A.5.a2; nine of them possessed H275Y substitution in the NA gene, a genetic marker of oseltamivir resistance. Influenza A(H3N2) viruses belonged to subclade 3C.2a1b.2a.2 with the genetic group 2b being dominant. All 433 influenza B viruses belonged to subclade V1A.3a.2 encoding HA1 substitutions A127T, P144L, and K203R, which could be further divided into two subgroups. None of the influenza A(H3N2) and B viruses sequenced had markers of resistance to NA inhibitors. Thus, despite the continuing circulation of Omicron descendant lineages, influenza activity has resumed in full force, raising concerns about the intensity of fore coming seasonal epidemics.

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.

Human seasonal coronaviruses (hCoVs) are a group of viruses that affect the upper respiratory tract. While seasonal patterns and the annual variability of predominant hCoV species are well-documented, their genetic and species diversity in St. Petersburg and across Russia remains largely unexplored. In this study, we developed a two-pool, long-amplicon (900–1100 bp) PCR primer panel for the whole-genome sequencing of four seasonal hCoV species. The panel was validated using nasopharyngeal swab samples collected within the Global Influenza Hospital Surveillance Network (GIHSN) project. Over a period of six epidemiological seasons from 2017 to 2023, we retrospectively analyzed 14,704 nasopharyngeal swabs collected from patients hospitalized in St. Petersburg clinics. Of these samples, 5010 (34.07%) tested positive for respiratory viruses, with 424 (2.88% of all samples) identified as seasonal human coronaviruses. The assessment of species diversity showed that predominant hCoV species alternate between seasons. Whole-genome sequences for 85 seasonal human coronaviruses (hCoVs) with >70% genome coverage were obtained, including 23 hCoV-OC43, 6 hCoV-HKU1, 39 hCoV-229E, and 17 hCoV-NL63. These represent the first near-complete genomes of seasonal hCoVs from the Russian Federation, addressing a significant gap in the genomic epidemiology of these viruses. A detailed phylogenetic analysis of the sequenced genomes was conducted, highlighting the emergence of hCoV-229E subclades 7b.1 and 7b.2, which carry numerous substitutions in the Spike protein. Additionally, we sequenced a historical hCoV-229E isolate collected in the USSR in 1979, the oldest sequenced 229E virus from Eurasia, and demonstrated that it belongs to Genotype 2. The newly developed PCR-based sequencing protocol for seasonal hCoVs is straightforward and well-suited for genomic surveillance, providing a valuable tool to enhance our understanding of the genetic diversity of human seasonal coronaviruses.

A wide variety of zoonotic viruses that can cross the interspecies barrier promote the emergence of new, potentially pandemic viruses in the human population that is often accompanied by the disappearance of existing circulating strains. Among the various reasons underlying this phenomenon is the strengthening of herd immunity by expanding the immune layer of population and improving means and methods of medical care. However, natura abhorret vacuum, and new pathogens come to replace disappearing ones. Over the past ten years, humanity has faced two pandemics: swine flu A(H1N1)pdm09 in 2009 and COVID-19 in 2019, providing scientists with a unique opportunity to learn more about a relationship between respiratory viruses and their pathogenesis. Together with viruses of pandemic significance, a large number of seasonal respiratory viruses circulate, which contribute to the structure of human morbidity, and coinfections aggravate the condition of the illness. In the conditions of the spread of new viruses with unexplored characteristics, in the absence of means of prevention and therapy, it is especially important to prevent the aggravation of morbidity due to mixed infections. Here we review the mutual involvement of pandemic influenza A(H1N1)pdm09 and SARS-CoV-2 coronavirus and seasonal respiratory viruses in the epidemic process, discuss some issues related to their spread, potential causes affecting the spread and severity of the morbidity. The given facts testify to the existence of seasonality and temporal patterns of the beginning and end of respiratory viruses circulation. Interestingly, the beginning of circulation of the pandemic influenza A(H1N1)pdm09 virus led to a shift in the timing and intensity of circulation of some respiratory viruses, which is probably caused by existence of “replication conflicts” between them, and did not affect others. Coinfection with SARS-CoV-2-19 and other respiratory viruses, especially respiratory syncytial virus and rhinoviruses, was quite often observed. At the current stage, no aggravating effect of influenza on the course of COVID-19 in mixed infection has been established. Whether this is due to the mild course of influenza infection in the 2020 epidemic season, or the competitive impact of SARS-CoV-2 on influenza viruses is not yet clear. Experts are still at the stage of accumulating facts and working on creating means of effective prevention and treatment of the new coronavirus infection.

The Omicron variant of SARS-CoV-2 rapidly spread worldwide in late 2021–early 2022, displacing the previously prevalent Delta variant. Before 16 December 2021, community transmission had already been observed in tens of countries globally. However, in Russia, the majority of reported cases at that time had been sporadic and associated with travel. Here, we report an Omicron outbreak at a student dormitory in Saint Petersburg between 16–29 December 2021, which was the earliest known instance of a large-scale community transmission in Russia. Out of the 465 sampled residents of the dormitory, 180 (38.7%) tested PCR-positive. Among the 118 residents for whom the variant had been tested by whole-genome sequencing, 111 (94.1%) were found to carry the Omicron variant. Among these 111 residents, 60 (54.1%) were vaccinated or had reported a previous infection of COVID-19. Phylogenetic analysis confirmed that the outbreak was caused by a single introduction of the BA.1.1 sub-lineage of the Omicron variant. The dormitory-derived clade constituted a significant proportion of BA.1.1 samples in Saint Petersburg and has spread to other regions of Russia and even to other countries. The rapid spread of the Omicron variant in a population with preexisting immunity to previous variants underlines its propensity for immune evasion.