Zinc is one of the important trace elements of blood. It helps in maturation of immune system in our body. In the past studies originate the relationship between viral disease and serum zinc deficiency. This was a multicenter case-control study to measure the serum zinc level of COVID-19 patients with different respiratory supports and to evaluate the Odds Ratio (OR) and Relative risk (RR) of zinc deficiency for oxygen requirement for COVID-19 patients. Study places were COVID-19 unit of three tertiary hospitals of Sylhet, a Northern district of Bangladesh. There were 30 controls and 90 cases in this study. The mean zinc level of cases (53-38mcg/dl) was significantly (p=0.000072) lower than the level of controls (73-23mcg/dl). The mean zinc level of the COVID-19 patients required oxygen (49-33mcg/dl) was significantly (p=0.0054) lower than the patients were not treated by oxygen therapy (64-51mcg/dl). The RR of getting affected by COVID-19 was 1-91 for the low zinc level people. Among the COVID-19 affected participants the lower zinc level people had a RR of 1-93 to receive oxygen supplementation. Lower zinc level people are more likely to be affected by COVID-19 in comparison to the normal zinc level people. Among the COVID-19 patients the lower zinc level people had nearly double (RR 1-93) risk of becoming hypoxic and eventually prone for oxygen support.