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.
ABSTRACT
BACKGROUND: The SARS-CoV-2 Omicron variants BA.2.74, BA.2.75, and BA.2.76 have appeared recently in India and have already spread to over 40 countries. They have acquired additional mutations in their spike protein compared to BA.2, branching away on the SARS-CoV-2 phylogenetic tree. These added mutations have raised concerns about the impact on viral pathogenicity, transmissibility, and immune evasion properties of the new variants. MATERIAL AND METHODS: A total of 990 Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) positive SARS-CoV-2 samples, with a cycle threshold value (Ct) less than 25, were processed for SARS-CoV-2 whole genome sequencing between June 3, 2022 to August 7, 2022. All corresponding demographic and clinical data were recorded and analyzed using Microsoft® Excel. RESULTS: Out of 990 samples sequenced, BA.2.75 (23.03%) was the predominant Omicron sublineage, followed by BA.2.38 (21.01%), BA.5 (9.70%), BA.2 (9.09%), BA.2.74 (8.89%) and BA.2.76 (5.56%). A total of 228 cases of BA.2.74, BA.2.75, and BA.2.76 were contacted by telephone, of which 215 (94.30%) were symptomatic with mild symptoms, and 13 (5.70%) had no symptoms. Fever (82.02%) was the most common symptom, followed by cough (49.12%), cold (35.97%), fatigue (27.19%), headache (21.05%), and myalgia (20.61%). Of the 228 cases, 195 (85.53%) cases recovered at home, and 33 (14.47%) required institutional quarantine. Recovery with conservative treatment was observed in 92.98% of cases, while 4.83% required additional oxygen therapy. Only three (1.32%) cases had poor outcomes resulting in death, and the remaining 225 (98.68%) survived. Among the 228 cases, 219 (96.05%) cases were vaccinated with the COVID-19 vaccine; of these, 72.60% had received both doses, 26.03% had also received the precautionary booster dose, while 1.37% were incompletely vaccinated with a single dose of vaccine. CONCLUSION: The current study indicates that the three BA.2 sublineages are causing mild disease in India. However, BA.2.75 has key mutations that are notable for accelerated growth and transmission and require close and effective monitoring.