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Background: SARS-coronavirus-2 has caused large number of infections globally. The infections have presented in a wave form in most of the countries. There have been differences in the clinical presentation, course, and the outcomes in the different waves.

Aim: This study describes the clinical features and course of the patients admitted with COVID-19 illness between the first and second wave of COVID-19 in a tertiary care center in South India.

Materials And Methods: This was a cross-sectional study where case record analysis of the patients admitted with moderate and severe COVID-19 illness in a tertiary care center in South India was performed. Patients admitted between August 1, 2020, and November 30, 2020, were considered to be affected in the first wave and those admitted between April 30, 2021, and July 30, 2021, were considered to be in the second wave of COVID-19. First wave and second wave periods were determined by a steep surge in infections in India as per the epidemiological data. The symptoms, comorbidities, clinical profile, severity, laboratory parameters, need for assisted ventilation, medications used, and outcome were compared between the two-time frames.

Results: A total of 123 patients' data were analyzed in each wave. 72 (58%) patients had fever, while 64 (52%) patients had fever in COVID second wave. In the first wave, five (4%) patients had diarrhea, and four (3.2%) patients had vomiting, whereas in second wave, 43 (34%) patients had diarrhea, and 25 (20 percent) patients had vomiting (P < 0.001). It was seen in the present study that more number of patients in the age group of 31 to 40 years had more serious illness and adverse outcomes in second wave compared with patients in first wave where age group of 51-60 years was more seriously affected. In COVID first wave, 80 (65.0%) were having moderate COVID-19 illness and 43 (35%) had severe illness. In the second wave, 70 (57%) had moderate illness and 53 (43%) patients had severe illness. In the first wave, 31 patients (25%) required non-invasive ventilation (NIV), whereas 79 patients (64%) required NIV in second wave (P < 0.001). First wave resulted in 12 (9.7%) deaths, whereas second wave resulted in 20 (16.2%) deaths.

Conclusion: The patients with COVID-19 illness in the second wave presented with more non-respiratory symptoms like vomiting, diarrhea, and joint pains. The patients who had severe illness in the second wave were comparatively younger than the patients of the first wave. The requirement of ventilatory support and immunosuppressants was more in the second wave.