Impact of Zinc Supplementation on Mortality and ICU Stay in COVID-19 Patients: A Systematic Review and Meta-analysis

Abstract

Background: The COVID-19 pandemic has affected healthcare globally. Vitamins supplementation has gained attention for adjunctive therapy. In particular, zinc has been known for its antiviral and immunomodulatory properties, making it a potential therapeutic option for COVID-19. Therefore, this systematic review aimed to evaluate the impact of zinc supplementation on clinical outcomes in ICU COVID-19 patients, namely mortality rates, intensive care unit (ICU) admission rate, and the length hospital stays. Methods: This review followed the PRISMA and the Cochrane Handbook guidelines. Eligible studies were published in English from December 2019 onward, while studies on other supplements, or involving children or pregnant women were excluded. A systematic search across PubMed, ScienceDirect, and Web of Science identified relevant studies. Study quality was assessed using the revised version of Cochrane risk of bias (RoB-2) tool for randomized clinical trials (RCTs), and the modified version of Newcastle for observational studies. Results: The search results yielded 1442 findings, out of them, eight studies were included. The reviewed studies included 2185 participants, primarily males aged 18–72. The primary outcomes showed that zinc supplementation significantly reduced mortality, with a pooled odds ratio of 0.57 (95% CI: 0.41–0.79, P = 0.0006), indicating a 43% lower mortality risk. There was no heterogeneity across the studies (I² = 0). Secondary outcomes showed reduced hospital stays and symptom duration in some studies but inconsistent effects on hospitalization rates, ventilation need, or ICU care.  Conclusions: This review concluded that zinc supplementation significantly reduced mortality in COVID-19 patients. While zinc showed some benefits in reducing hospital stays and improving inflammatory markers, its effects on ICU admissions, ventilation, and overall recovery were inconsistent. Further research is needed to determine its optimal use and long-term clinical significance.