Hydroxychloroquine Can’t Prevent COVID-19, Study Finds

hydroxychloroquine tablets


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Key Takeaways

  • Hydroxychloroquine is no more effective at preventing COVID-19 than a placebo. 
  • In a clinical trial, hospital workers with a high risk of COVID-19 exposure took the drug every day for two months.
  • The antimalarial drug was previously approved to treat COVID-19, but the FDA revoked this approval.

Hydroxychloroquine is not effective at preventing COVID-19 in those with the highest risk of exposure.

In a clinical trial from the Perelman School of Medicine at the University of Pennsylvania, researchers found no difference in infection rates of hospital workers who took daily doses of hydroxychloroquine versus those who took a placebo. The results were published online in JAMA Internal Medicine on Wednesday. 

“This work represents the first randomized trial of hydroxychloroquine’s prophylactic (preventative) effect for those not yet exposed to COVID-19,” study lead author Benjamin Abella, MD, MPhil, a professor of Emergency Medicine and the director of Penn Medicine’s Center for Resuscitation Science, said in a news release. “And while hydroxychloroquine is an effective drug for the treatment of diseases like lupus and malaria, we saw no differences that would lead us to recommend prescribing it as a preventive medication for COVID-19 in front line workers.”

Hydroxychloroquine has been a matter of controversy since the early days of the pandemic, when it was introduced as a possible treatment for COVID-19. While the Food and Drug Administration (FDA) granted emergency use authorization for both hydroxychloroquine and chloroquine products in March, it revoked the authorization by June, citing ineffectiveness and a risk of serious cardiac events. 

What Is Hydroxychloroquine Intended To Treat?

Hydroxychloroquine is FDA-approved to treat and prevent malaria. It is also approved to treat lupus and rheumatoid arthritis.

Even though the FDA deemed the drug unfit for COVID-19 treatment, its potential role in prevention was less clear. The UPenn study is the first to offer evidence that there’s no statistically significant benefit to taking hydroxychloroquine to reduce COVID-19 risk.

Out of 125 physicians, nurses, certified nursing assistants, emergency technicians, and respiratory therapists evaluated in the study—all of whom had direct contact with COVID-19 patients—half took 600 milligrams (mg) of hydroxychloroquine every day for eight weeks, while the other half took a placebo. Neither the participants nor the researchers knew who was taking the drug versus the placebo. 

By the end of the study, 6.3% of the hospital employees taking hydroxychloroquine had contracted COVID-19, compared to 6.6% of the employees taking a placebo. This indicates the drug has no clinical benefit for prevention of COVID-19. 

Employees were tested for COVID-19 at the beginning, middle, and end of the study, and given electrocardiograms (ECGs) to screen for any heart problems associated with hydroxychloroquine. Researchers detected no difference in heart rhythms among each group, suggesting that while hydroxychloroquine was not an effective prevention method, it was also not harmful. 

The study did have its drawbacks. It was terminated early before reaching the intended 200 participants because researchers decided more participation wouldn’t influence results. In addition, 125 people is a relatively small sample size, and most of the study participants were young and healthy. The participants who contracted COVID-19 were either asymptomatic or experienced only mild symptoms. 

What This Means For You

In lieu of a miracle drug, researchers say efforts are best focused on creating a vaccine to prevent COVID-19. In the meantime, masks, social distancing, and frequent hand washing are your best preventive measures. 

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Abella BS, Jolkovsky EL, Biney BT, et al. Efficacy and safety of hydroxychloroquine vs placebo for pre-exposure SARS-CoV-2 Prophylaxis among health care workers: A randomized clinical trial. JAMA Intern Med. doi:10.1001/jamainternmed.2020.6319

  2. Food and Drug Administration. Emergency Use Authorization.

  3. Food and Drug Administration. FDA cautions against use of hydroxychloroquine or chloroquine for COVID-19 outside of the hospital setting or a clinical trial due to risk of heart rhythm problems.

By Anisa Arsenault
Anisa joined the company in 2018 after managing news surrounding fertility, pregnancy, and parenting for The Bump. Her health and wellness articles have appeared in outlets like Prevention and Metro US. At Verywell, she is responsible for the news program, which includes coverage of COVID-19.