Background: In pandemic situations, it is essential that the limited resources are used judiciously to achieve most benefits. Prediction of the disease severity at the earliest will help in better allocation, thus, pos. affecting prognosis and treatment. Objective: To investigate patient characteristics and specific biomarkers as possible early predictors of disease severity of SARS-COV-2 infection. Method: Retrospective single-centric observational study conducted at 70-bedded intensive care unit of tertiary care hospital at Haryana, India. 100 consecutive RT-PCR pos. COVID-19 adult patients. Demographics, Apache-II score, and Inflammatory markers were compared with respect to oxygenation defect (PaO2/FiO2 ratio: <300 or ≥300 mm Hg), need of invasive ventilation, ICU length of stay and 28-day mortality. Findings: Mean age was significantly more in lower PF Ratio group (58.01 ± 15.33 vs 50.97 ± 13.78, p = 0.023) whereas sex ratio was comparable among patients in two groups. Significantly, higher APACHE-II score (p≤0.001) and presence of hypertension (43.54% vs 23.68%; p = 0·045) in low PF Ratio group along with higher C-reactive protein (171.78 ± 124.45 vs 101.52 ± 88.70), IL-6 (173.51 vs 53.18) and ferritin (1677.60 ± 2271.13 vs 643.54 ± 718.68) levels. Procalcitonin, lactate dehydrogenase, and creatine phosphokinase (CPK) levels were not significant. Interpretation: Age and APACHE II score and among laboratory parameters CRP, ferritin, and IL-6 levels were significantly higher in low PF Ratio group, patients requiring invasive ventilation and in mortality group. Use of this triad (CRP, ferritin, and IL-6 levels) at admission may predict the disease severity early in the course. Addition of APACHE-II may further improve the accuracy of the score.