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New Cleveland Clinic study shows zinc, vitamin C aren't effective in treating COVID-19

The study found neither drug decreases severity or duration of symptoms.

CLEVELAND — EDITOR'S NOTE: The video in the player above originally aired on November 10, 2020.

It was once thought to possibly have a positive effect on a person’s ability to fight off COVID-19. Now, Cleveland Clinic researchers say, zinc or vitamin C, or a combination of both, do not significantly lessen the severity of symptoms in patients with COVID-19.

The findings of the study, called the COVIDAtoZ clinical trial, were published Friday in JAMA Open Network.

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The trial focused on 214 adult patients who had confirmed cases of COVID-19. Patients either received ten days of zinc gluconate (50 mg), vitamin C (8000 mg), both or standard care from April to October 2020. 

The study was eventually stopped because the supplements were showing no significant differences among the four groups.

“When we began this trial, there was no research to support supplemental therapy for the prevention or treatment of patients with COVID-19,” said Milind Desai, M.D., MBA, director, clinical operations in Cleveland Clinic’s Heart Vascular & Thoracic Institute and co-principal investigator of the study. “As we watched the pandemic spread across the globe, infecting and killing millions, the medical community and consumers alike scrambled to try supplements that they believed could possibly prevent infection, or ease COVID-19 symptoms, but the research is just now catching up. While vitamin C and zinc proved ineffective as a treatment when clinically compared to standard care, the study of other therapeutics continues.”

Patients in the study were not admitted to the hospital but did see a physician on an outpatient basis.

“We know that not all patients with COVID-19 require hospital admission, and compared to those being treated in a hospital setting, they are more likely to be seeking out supplements that could help them, so it was an important population to study,” said Suma Thomas, M.D., MBA, vice-chairman of strategic operations in Cleveland Clinic’s Heart Vascular & Thoracic Institute and co-principal investigator of the study.

Zinc is widely known to be important for the immune system’s function. It also has a role in antibody and white blood cell production. Vitamin C can reduce damage to cells. Both have been shown to help fight infection.

A total of four adverse events were observed during the trial, including 3 deaths. The data safety monitoring board, however, did not believe that any of those events were caused by treatments patients received as a part of the study.

There are steps everyone can take to reduce the risk of infection. When possible, get a COVID-19 vaccine. Continue to socially distance, wash your hands often, and wear a mask in public.

Editor's Note: The below video aired on February 11, 2021

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