Comparison of Clinical Presentation and Vaccine Effectiveness Among Omicron and Non-omicron SARS Coronavirus-2 Patients.

Introduction The rapidly mutating Omicron SARS-CoV-2 variant has replaced the previous dominant SARS-CoV-2 variants like alpha, and delta resulting in the amplification of coronavirus disease 2019 (COVID-19) cases. The present study was conducted to compare the clinical profile and vaccination status in patients infected with Omicron and non-Omicron SARS-CoV-2 variants. Methods All patients who tested positive for coronavirus disease 2019 (COVID-19) during the study period (January 2022 to February 2022) were further tested for detection of SARS-CoV-2 Omicron variant by using Omisure kit (TATA MD CHECK RT-PCR, TATA MEDICAL AND DIAGNOSTICS LIMITED, Tamil Nadu, INDIA). Clinico-demographic factors and vaccination status were compared between both Omicron and non-Omicron groups. Results A total of 1,722 patients who tested positive for COVID-19 were included in the study, of which 656 (38.1%) were Omicron and 1,066 (61.9%) were non-Omicron SARS-CoV-2 variants. Blood group and vaccination status were the major predictors for Omicron. The proportion of male patients was 58.4% in the Omicron group and 57.9% in the non-Omicron group. Maximum cases (86.2%) belonged to >18-60 years age group, 7.3% to >60 years age group, and least to 0-18 years (6.5%). The average age of the study participants was 35.4 ± 14.5 years. Vaccinated participants had less chance of having Omicron than the unvaccinated participants (p-value - 0.003). Fever and loss of smell were found to be significantly associated with the non-Omicron SARS-CoV-2 variant. (p-value < 0.05). Conclusion The present study reflects that the clinical course of the disease is milder in Omicron as compared to the non-Omicron variant. However rapid rise in cases can badly affect the healthcare system demanding good preparedness to tackle all the predicaments. Good Vaccination coverage should be of utmost priority irrespective of the variant type.