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VIZIR RCT – Zinc for COVID-19?

February 9, 2023

Written by Sam Parnell

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Zinc supplementation for patients with COVID-19 decreased 30-day ICU admission rates and led to shorter hospital stays. Subgroup analysis showed these effects were especially pronounced for elderly patients and those with comorbid conditions.

Why does this matter?
While the COVID-19 pandemic appears to be waning, SARS-CoV-2 continues to be associated with significant morbidity and mortality across the globe. We now have several effective vaccines and medications in our arsenal to combat COVID-19. However, additional treatment modalities may be needed as the SARS-CoV-2 virus continues to mutate and evolve. Zinc has been associated with immune system function and antiviral effects, but could this simple, cheap, and abundant mineral have a role in treatment of COVID-19?

To paraphrase Descartes, “I think, therefore I zinc.”
This was a prospective, randomized, double-blind, placebo-controlled trial of 470 patients with COVID-19 in Tunisia. Patients were excluded if they had severe comorbid conditions (including heart, liver, or renal failure), history of malignancy, poor mental status, or need for immediate ICU admission. In addition, patients were excluded if symptoms were ongoing more than 7 days. Patients in the zinc group received 25 mg of elemental zinc twice a day for 15 days. The control group received a placebo.

Patients who received zinc had decreased ICU admission rate, 5.2% vs 11.3%; OR 0.43 (95%CI 0.21–0.87), shorter length of hospital stay, difference 3.5 days (95%CI 2.76–4.23), and decreased symptom duration, difference 1.9 days (95%CI 0.62–2.6). There was also a non-significant decrease in mortality in the zinc group: 6.5% vs 9.2%; OR 0.68 (95%CI 0.34–1.35). Subgroup analysis showed a positive treatment effect in inpatients, patients > 65 years, patients with comorbidities, and those requiring oxygen at baseline. No serious adverse effects were reported.

This trial had several limitations, and additional studies are needed to determine the impact and generalizability of zinc treatment for COVID-19. However, zinc supplementation has several advantages compared to other treatment modalities for COVID-19. It is widely available over the counter, low cost, and exceedingly safe.

Despite its limitations, this was a promising study. Based on these results, I plan to recommend zinc supplementation to patients with COVID-19. 

Editor’s note: The study enrolled moderately severe, largely unvaccinated (20%) patients. Although it was funded by a pharmaceutical company, that is probably not a big deal – as Nick Zelt joked, “Big Zinc is at it again.” I wonder if results would have been significantly different in a vaccinated population. Notably, zinc is not recommended by current NIH treatment guidelines, though this study has not yet been included as a reference. Regardless, I see little downside in instructing COVID patients to take a zinc supplement twice a day. ~Clay Smith

Twice-Daily Oral Zinc in the Treatment of Patients With Coronavirus Disease 2019: A Randomized Double-Blind Controlled Trial. Clin Infect Dis. 2023;76(2):185-191. doi:10.1093/cid/ciac807