Since the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, caused by the severe respiratory syndrome coronavirus 2 (SARS-CoV-2), millions of people have died, and the medical system has faced significant difficulties. Our purpose was to perform a meta-analysis to estimate the effect of vitamin C on in-hospital mortality and the ICU or hospital length of stay for patients diagnosed with COVID-19. We conducted a systematic review with meta-analysis in the following databases: PubMed, Web of Science, Scopus and Cochrane Central Register of Controlled Trials. We included studies that evaluated the effect of vitamin C supplementation, compared with standard treatment in COVID-19 patients who are ≥18 y of age. Nineteen trials were included in the meta-analysis. In-hospital mortality with and without vitamin C supplementation was 24.1% vs. 33.9% (OR = 0.59; 95%CI: 0.37 to 0.95; p = 0.03), respectively. Sub-analysis showed that, in randomized clinical trials, in-hospital mortality varied and amounted to 23.9% vs. 35.8% (OR = 0.44; 95%CI: 0.25 to 0.76; p = 0.003), respectively. In the non-randomized trials, in-hospital mortality was 24.2% vs. 33.5% (OR = 0.72; 95%CI: 0.38 to 1.39; p = 0.33), respectively. The ICU length of stay was longer in patients treated with vitamin C vs. standard therapy, 11.1 (7.3) vs. 8.3 (4.7) days (MD = 1.91; 95%CI: 0.89 to 2.93; p < 0.001), respectively. Acute kidney injury in patients treated with and without vitamin C varied and amounted to 27.8% vs. 45.0% (OR = 0.56; 95%CI: 0.40 to 0.78; p < 0.001), respectively. There were no differences in the frequency of other adverse events among patients’ treatment with and without vitamin C (all p > 0.05). The use of vitamin C reduces hospital mortality. The length of stay in the ICU is longer among patients treated with vitamin C. In terms of patient safety, vitamin C has an acceptable profile. Low doses of vitamin C are effective and safe. Despite some evidence of the usefulness of vitamin C in modifying the course of COVID-19, it is too early to modify guidelines and recommendations. Further studies, in particular randomized clinical trials, are necessary.

Introduction and Objective.Zinc is a trace element that plays a role in stimulating innate and acquired immunity. The aim of the study was to determine the antiviral effect of the administration of zinc in COVID-19 patients. Materials and Method.A literature search was performed in P Web of Science, PubMed, Scopus and Cochrane databases from 1 January 2020 -22 August 2022. In addition, reference lists of the included articles and their related citations in PubMed were also reviewed for additional pertinent studies. Results. A total of 9 eligible studies were identified. In-hospital mortality in zinc supplementation patients, and patients treated without zinc, varied and amounted to 21.6% vs. 23.04% difference (OR=0.71; 95%CI: 0.62-0.81; p<0.001). 28-day to 30-day mortality in patients treated with zinc was 7.7%, compared to 11.9% for patients treated without zinc (OR=0.61; 95%CI: 0.35-1.06; p=0.08). In-hospital adverse events among patients treated with and without COVID-19 did not show any statistically significant differences in relation to acute kidney injury occurrence (12.8% vs. 12.4%, respectively; OR=0.63; 95%CI: 0.19-2.12; p=0.45, as well as need for mechanical ventilation (13.2% vs. 14.1%; OR=0.83; 95%CI: 0.52-1.32; p=0.43). Conclusions. Zinc supplementation is associated with lower COVID-19 in-hospital mortality. Additionally, it is risk-free in COVID-19 patients since there have been no negative side effects, such as acute renal damage or the requirement for mechanical ventilation compared to patients without COVID-19. Due to scientific evidence and the role it represents in the human body, zinc supplementation should be taken into consideration for COVID-19 patients as an adjunct therapy.