Omicron SARS-CoV-2 variant: An observational study from a hospital in Southern India

Abstract Introduction The Omicron variant rapidly outpaced Delta with documented community transmission in most countries and has led to an upsurge in cases in most regions. Since its initial detection from a specimen collected on November 8th 2021, Omicron amounted to 74.0% of the genome sequenced in South Africa and more than 99.0% in rest of the world. Objectives 1. To describe the socio-demographic and clinical profile of Omicron cases treated at our tertiary care institution. 2. To assess the factors associated with the vaccination status of such Omicron cases. Methods This observational study was conducted at a 500 bedded hospital in southern India from 15th of December 2021 to 5th of February 2022. Of the 333 COVID-19 patients who were registered with Reverse Transcription-Polymerase Chain Reaction (RT-PCR) positive result along with S Gene Target Failure (SGTF), 203 patients were included and were interviewed using a pre-designed semi-structured questionnaire. With prior approval from the Institutional Ethics Committee (IEC) data was collected and statistically analyzed with descriptive statistics and inferential statistics using SPSS software trial version 28.0 and OpenEpi software. At 95% confidence level, a P value of < 0.05 was considered as statistically significant. Results Of the 203 cases studied, majority 149 (73.4%) were symptomatic, of which almost 114 (76.5%) had fever, 72 (48.3%) had cough and 29 (19.5%) had myalgia. 193 (95.1%) cases were categorized as mild, 8 (3.9%) as moderate and 2 (1.0%) as severe cases of COVID-19 with SGTF. Only 10 (4.9%) patients received supplementary oxygen support. Almost 158 patients (77.8%) were vaccinated against COVID-19 of which 106 (67%) were vaccinated with Covishield vaccine followed by 50 (31.7%) of them with Covaxin. 126 (79.7%) patients were completely vaccinated with two doses of any COVID-19 vaccine and 32 (20.3%) were partially vaccinated with a single dose of any COVID-19 vaccine. Among those who required supplemental oxygen (n = 10), the proportion of those vaccinated (40.0%) was lower com pared to those who were unvaccinated (60.0%). This association was statistically significant (P = 0.003, OR = 0.169, 95% CI of OR = 0.045, 0.628). Among the completely vaccinated subjects (n = 125), there was a statistically significant difference in mean (95% CI) interval between the last dose of vaccine taken and date of RT-PCR positivity with SGTF (P < 0.001). It was 186 (162, 210) days for Covaxin and was 131 (114, 148) days for Covishield vaccine. Conclusion Omicron (SGTF) cases manifests mostly as mild cases with symptoms like fever, cough, myalgia and majority were independent of oxygen supplementation and had good prognosis. Omicron infection was delayed over six months among completely vaccinated subjects especially those who were vaccinated with Covaxin.