Clinical profile of patients infected with suspected SARS-CoV-2 Omicron variant of concern, Tamil Nadu, India, December 2021-January 2022

• Published in: Indian journal of medical research (New Delhi, India : 1994) Vol. 155; no. 1; pp. 165 - 170
• Main Authors: Raju, Mohan, Vivian Thangaraj, Jeromie, Selvavinayagam, T, Somasundaram, A, Parthipan, K, Sivadoss, Raju, Sabarinathan, R, Subramaniam, Sudharshini, A. Rozario, Amanda, Rani, Sudha, Suganya, E, Murhekar, Manoj
• Format: Journal Article
• Language: English
• Published: India Wolters Kluwer India Pvt. Ltd 01-01-2022; Scientific Scholar; Wolters Kluwer - Medknow
• Subjects: Coronaviruses; COVID-19; Original; Severe acute respiratory syndrome coronavirus 2; Testing laboratories; Tamil Nadu India; India; B.1.1.529 - COVID-19 - epidemiology - Omicron - SARS-CoV-2 - severity - variant of concern
• ISSN: 0971-5916; 0975-9174
• DOI: 10.4103/ijmr.ijmr_312_22

Background & objectives: COVID-19 cases have been rising rapidly in countries where the SARS-CoV-2 variant of concern (VOC), Omicron (B.1.1.529) has been reported. We conducted a study to describe the epidemiological and clinical characteristics and outcomes of COVID-19 patients with 'S' gene target failure (SGTF, suspected Omicron). Furthermore, their clinical outcomes with COVID-19 patients with non-SGTF (non-Omicron) were also compared.
Methods: This study was conducted in Tamil Nadu, India, between December 14, 2021 and January 7, 2022 among patients who underwent reverse transcription-PCR testing for SARS-CoV-2 in four laboratories with facilities for S gene screening. Consecutively selected COVID-19 patients with SGTF were telephonically contacted, seven and 14 days respectively after their date of positive result to collect information on the socio-demographic characteristics, previous history of COVID-19, vaccination status and clinical course of illness along with treatment details. To compare their outcomes with non-SGTF patients, one randomly suspected non-Omicron case for every two suspected Omicron cases from the line-list were selected, matching for the date of sample collection and the testing laboratory.
Results: A total of 1175 SGTF COVID-19 patients were enrolled for this study. Almost 6 per cent (n=72) reported a history of previous infection. 141 (13.5%) suspected Omicron cases were non-vaccinated, while 148 (14.2%) and 703 (67.4%) had received valid one and two doses of COVID-19 vaccines, respectively. Predominant symptoms reported included fever (n=508, 43.2%), body pain (n=275, 23.4%), running nose (n=261, 22.2%) and cough (n=249, 21.2%). Five (0.4%) of the 1175 suspected Omicron cases required oxygen supplementation as compared to ten (1.6%) of the 634 suspected non-Omicron cases. No deaths were reported among omicron suspects, whereas there were four deaths among suspected non-Omicron cases.
Interpretation & conclusions: Majority of the suspected Omicron cases had a mild course of illness. The overall severity of these cases was less compared to the suspected non-Omicron cases.