Omicron variants of SARS-CoV-2: Epidemiological and Clinical Insights from a Tertiary Care Center in Saudi Arabia

Background The actual burden of the Omicron variants remains unclear. Therefore, this study aims to analyze the epidemiological and clinical features of Omicron-infected patients and investigate factors influencing hospital admission. Methods This retrospective single-center study included individuals with positive SARS-CoV-2 infection, specifically the Omicron variants (XBB, EG or JN), identified through real-time reverse-transcriptase polymerase chain reaction assays from January 2022 to December 2023. Results A total of 305 Omicron-infected patients were included; (53.11%) were females and (46.89%) were males, with a median age of 39 years [interquartile range (IQR): 30, 53]. Underlying diseases, including endocrine/metabolic disorders (22.30%), hypertension (12.79%), chronic respiratory disease (10.49%), and malignancy (9.18%) were prevalent, while (40.98%) were medically free. The XBB variant was predominant (73.11%), followed by JN (20.33%), and EG variant (6.56%). The seasonality analysis demonstrates XBB variants' domination in 2022, with a surge to 40 cases in December. The trend continued in 2023, peaking at 76 XBB cases in March. May 2023 reported 38 XBB cases and the emergence of 17 EG instances. Notably, in December, only one XBB case was reported, and 62 instances emerged with the JN variant. Overall, 233 out of 305 cases were reported during flu season (September to March) (76.39%). Moreover, hospitalization occurred in (16.39%), with a (1.31%) mortality rate (all deaths in the JN variant). Multivariable analysis confirmed renal disease, chronic respiratory disease, endocrine/metabolism issues, and polymicrobial infection as positive predictors of hospitalization (p<0.05). While COVID-19 vaccination significantly reduced hospitalization odds (Odds Ratio: 0.20, p =0.001). Conclusions These findings contribute valuable insights into Omicron epidemiology and factors influencing hospitalization. The dynamic fluctuations in Omicron variants, particularly XBB, EG, and JN, over 2022 and 2023, with JN emerging as the dominant circulating variant globally, underscore the need for continuous vigilance and urgency for updated vaccine formulations.