Introduction
Respiratory Syncytial Virus (RSV) is a common viral pathogen that causes 64 million acute respiratory infections annually1. RSV is considered as a major cause of lower respiratory tract infections amongst young children, elderly and immunocompromised adults worldwide2-5, and is a frequent cause of hospitalization6,7. In a recent systematic analysis, it was associated to 6.6 million of acute lower respiratory infection, where more than 1 million were hospitalized and 10000 dead in the hospital8. For example, in the United States, RSV infections cause between 58,000 and 80,000 hospitalizations each year in children under 5 years of age and between 60,000 and 160,000 in adults over 65 years of age9.
Based on the differences in the nucleo­tide sequence in the G protein, RSV is divided into 45 genotypes. RSV-A has 15 genotypes whereas RSV-B has 30 genotypes. Different RSV genotypes exhibit different pathogenicities. In the same period and area, different RSV genotypes can be co-epidemic, but most epidemics are dominated by one of the subgroups or genotypes10. In the context of COVID-19 pandemic with resulting quarantine and barrier measures, a drastic reduction of RSV infections has been observed in Europe and North America1. Genetic characterization of RSV by direct sequencing of sub-genomic regions or full genomic sequencing will be an important part of RSV surveillance to monitor potential antigenic changes in the circulating viruses that might affect the efficacy of future immunization strategies. In general, the preferred RSV surveillance will be an active sentinel system, with both primary care and hospital patients being systematically sampled and tested for RSV11. At present, data concerning the molecular epidemiological characteristics of RSV subtypes are limited12.
No effective therapy or vaccine is available to date, but vaccine candidates and monoclonal antibodies are in late clinical development5. Lately, a new monoclonal antibody (nirsevimab) has been approved13,14. The effectiveness of these therapies may vary depending on the type of virus. Therefore, the reporting of RSV cases and the etiological diagnosis of the genotype are very important for planning future public health measures and allow appropriate treatment of the patient and avoidance of unnecessary therapies (such as antibiotics)15.
Here, we conducted a study detecting and genotyping RSV, circulating in clinical samples in Asturias from 2017 to 2022. The aim of this study is to know the incidence and distribution of RSV types and to enrich the data of epidemiological molecular studies on RSV in Spain.