Objective: To determine the clinical outcomes of older COVID-19 patients who received DMB compared to those who did not. We hypothesized that fewer patients administered DMB would require oxygen therapy and/or intensive care support than those who did not. Methodology: Cohort observational study of all consecutive hospitalized COVID-19 patients aged 50 and above in a tertiary academic hospital who received DMB compared to a recent cohort who did not. Patients were administered oral vitamin D3 1000 IU OD, magnesium 150mg OD and vitamin B12 500mcg OD (DMB) upon admission if they did not require oxygen therapy. Primary outcome was deterioration post-DMB administration leading to any form of oxygen therapy and/or intensive care support. Results: Between 15 January and 15 April 2020, 43 consecutive COVID-19 patients aged ≥50 were identified. 17 patients received DMB and 26 patients did not. Baseline demographic characteristics between the two groups were similar. Significantly fewer DMB patients than controls required initiation of oxygen therapy subsequently throughout their hospitalization (17.6% vs 61.5%, P=0.006). DMB exposure was associated with odds ratios of 0.13 (95% CI: 0.03 − 0.59) and 0.15 (95% CI: 0.03 − 0.93) for oxygen therapy need and/or intensive care support on univariate and multivariate analyses respectively. Conclusions: DMB combination in older COVID-19 patients was associated with a significant reduction in proportion of patients with clinical deterioration requiring oxygen support and/or intensive care support. This study supports further larger randomized control trials to ascertain the full benefit of DMB in ameliorating COVID-19 severity.