The University of Minnesota Medical School conducted a randomized clinical trial to evaluate the efficacy of hydroxychloroquine as a pre-exposure prophylaxis against COVID-19 in health care workers. The trial, which began on April 6, aimed to determine if hydroxychloroquine could prevent COVID-19 infection in individuals at high risk of exposure to the virus.
Participants, including 1,483 health care workers and first responders from across the U.S. and Canada, were randomly assigned to receive either once-weekly hydroxychloroquine, twice-weekly hydroxychloroquine, or a placebo. They were followed for a period ranging from four to twelve weeks to monitor the development of COVID-19.
The results, published in Clinical Infectious Diseases, showed that 7.9% of participants assigned the placebo developed COVID-19, compared to 5.9% of those assigned hydroxychloroquine. However, this difference was not statistically significant, indicating that hydroxychloroquine did not offer a meaningful protective effect against COVID-19 in this context.
Side effects were more common among participants taking hydroxychloroquine, with 31% of the once-weekly group and 36% of the twice-weekly group reporting issues, compared to 21% in the placebo group. The most frequently reported side effects included nausea, upset stomach, and diarrhea. Importantly, there was no increased risk of serious side effects or cardiac complications associated with hydroxychloroquine use compared to the placebo.
The research team included David Boulware, MD, MPH; Sarah Lofgren, MD; Caleb Skipper, MD; and Matthew Pullen, MD, from the U of M Medical School, along with statisticians and other collaborators from the University of Minnesota and other institutions. This study represents a significant contribution to understanding the limitations of hydroxychloroquine in preventing COVID-19 among high-risk populations.