A comparison of Delta and Omicron waves of COVID-19 pandemic: An observation from a tertiary care center from North India

Abstract

Objectives: The impact of the Omicron variant (B.1.1.529) was very low as compared to the Delta variant (B.1.617.2) in North India. Very few studies are there highlighting the clinical parameters associated with disease outcomes among coronavirus disease-2019 (COVID-19) patients during the Delta and Omicron waves of the pandemic. This study was conducted to observe various clinical parameters associated with disease outcomes among COVID-19 patients during Delta and Omicron waves. Materials and Methods: This retrospective observational study was conducted during the Delta wave (March 2021 to June 2021) and Omicron wave (December 2021 to March 2022) on patients with positive reverse transcriptase–polymerase chain reaction (RT-PCR) admitted during the study period. The patient characteristics and outcome measures including demographic, baseline clinical, disease severity, intensive care unit admissions, and hospital mortality were recorded. Results: Out of total of 1731 patients who tested positive for severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) by RT-PCR, 16 patients were admitted during the omicron wave and 878 were admitted during the Delta wave. The majority of admitted patients during the Delta wave were in the age groups of 21–40 and 41–60 years, with significantly less number of admissions in the age group of <20 years during the Omicron wave. The admissions were significantly lower during the Omicron wave (P < 0.001). Patients without a previous history of COVID-19 and unvaccinated status were having significantly higher admissions (P < 0.001). During Delta and Omicron waves 71.4% and 18.75% of the patients, respectively, were having no comorbidities. Conclusion: Hospital admissions were higher during the Delta wave in comparison to the Omicron wave. During the Delta wave, the degree of severity and number of deaths were also very high.