Among the variables found to be significant in the univariable analyses, BMI ≥ 30 kg/m2 (HR 2.301, 95% CI 1.614–3.283), days from symptom onset (HR 1.159, 95% CI 1.075–1.249), SpO2 < 97% (HR 1.861, 95% CI 1.355–2.557), lymphopenia < 1500/μL (HR 1.709, 95% CI 1.131–2.583), thrombocytopenia < 150 x 103/μL (HR 1.742, 95% CI 1.300–2.335), albumin < 4.0 g/dL (HR 1.871, 95% CI 1.292–2.708), LDH level (HR 0.999, 95% CI 0.998–1.000), and CRP elevation > 1.5 mg/dL (HR 3.021, 95% CI 2.141–4.261) remained significant risk factors for O2 supplementation via nasal prong in the multivariable analysis. Here, CRP is linked to lymphopenia.