Diversity of Omicron sublineages and clinical characteristics in hospitalized patients in the southernmost state of Brazil

Background Omicron has become the dominant variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) since first reported in November 2021. From the initially detected Wuhan lineage, sublineages BA.2, BA.4, BA.5, BQ, XAG, and XBB have emerged over time and are dominant in many countries. Therefore, the aim is to evaluate which variants are circulating and the clinical characteristics of inpatients infected with the Omicron variant. Methods This retrospective cohort study selected hospitalized patients admitted with respiratory symptoms to a hospital in the state of Rio Grande do Sul, Brazil, between June and July 2022. SARS-CoV-2 results were analyzed together with clinical outcomes and vaccination status. A viral genome library was prepared and forwarded to the Illumina MiSeq Platform for sequencing. Results In total, 37 genomes were sequenced. Concerning the Omicron sublineages, our study detected: BA.1 (21 K), BA.2 (21 L), BA.4 (22A), BA.5 (22B), BA.2.12.1 (22C), BQ.1 (22E), XBB (22F), and XAG recombinant. Omicron BA.5 (30%), BA.2 (19%), and BQ.1 (19%) were the most frequent sublineages, respectively. In total, 38% of patients present hypertension, and the most common symptoms were coughing (62%). Analyzing the COVID-19 vaccination, 30% of patients were fully vaccinated, 49% had a partial vaccination status, and 21% were unvaccinated (no dose). Conclusions BA.5 was the most prevalent sublineage in our study and surpassed the predominance of BA.2, as reported by the national genomic surveillance program. BQ.1 was diagnosed earlier in this study than it was officially reported in the state. Current data have demonstrated that the Omicron variant causes less severe infections, with the high rate of transmissibility and mutational landscape causing the rapid emergence of new sublineages.