Abstract
Background The SARS-CoV-2 Omicron variant, within two months of its detection, replaced the Delta variant to become the dominant circulating variant globally. Therefore, it is essential to understand the characteristics of the disease caused by the variant and its impact on vaccination. Methods A total of 165 confirmed Omicron cases attending a tertiary care hospital in Pune, Maharashtra, between December 2021 to February 2022 were studied. Their demographic, clinical, and immunization history was recorded. Results Among the 165 cases, 7.88% were B.1.1.529 Omicron cases, 25.45% were BA.1 Omicron cases, and 66.67% were BA.2 Omicron cases. Of these 165 patients, 146 (88.48%) were discharged after treatment, 12 (7.27%) died during hospitalization, and seven (4.24%) were brought dead. The presence of one or more comorbid conditions was seen in 15.15%, of which diabetes mellitus and hypertension (28% each) were the most common conditions. Older age (greater than 60 years), an important risk factor for poor outcomes, was present in 9.1% of cases. Among the 165 cases, vaccination with at least one dose of vaccine was found in 80.61% of cases. Out of 165 cases, clinical data was available for 158 cases. Of these 158 cases, 86.71% had symptoms, and 13.29% were asymptomatic. Fever, followed by cough, myalgia, runny nose, and headache, were the most common presenting symptoms. The mean duration of illness was 2.69 days, with 91.14% of cases having the illness for less than five days, and 89.24% of cases had a National Early Warning Score (NEWS) of 1-4, suggesting a good prognosis. In 93.90% of cases, the chest X-ray findings were normal. Of the 158 cases, 92.41% of cases recovered with supportive treatment, and only 7.59% of cases required oxygen therapy. Conclusion The current study shows that the Omicron variant caused mild disease with reduced need for hospital admission and oxygen therapy in India.