Insurers are covering the cost of the antiparasitic drug ivermectin to treat COVID-19, despite a lack of evidence about its safety and efficacy, a new study suggests.

The U.S. Food and Drug Administration has not authorized or approved ivermectin to treat COVID-19, in fact, Several statements against it have been issued. Clinical trials evaluating ivermectin tablets for the prevention and treatment of COVID-19 are ongoing. But a study published in JAMA by a team from the University of Michigan and Boston University found that oral ivermectin use surged 24-fold from December 2020 to March 2021, with insurers paying nearly 61% to 74% of the total cost.

By evaluating claims data, the authors estimated that of the 88,000 ivermectin prescriptions written in the week of August 2021, about 4% were for the drug’s approved uses. Before the pandemic, the Centers for Disease Control and Prevention said only 3,600 prescriptions for ivermectin were being written each week.

Insurers paid nearly $2.4 million for those prescriptions that week, according to the report. Looking at claims data for an entire year, the total is approximately $130 million.

“Insurers often don’t cover ineffective treatments, or at least make patients pay for most of the cost,” said study co-author Kao-Ping Chua. “Our study shows that they are treating ivermectin prescriptions differently for COVID-19. In doing so, they are reducing barriers for some people to replace COVID-19 vaccinations or evidence-based treatment with ineffective drugs.”

Chua, a pediatrician at Michigan Medicine Children’s Hospital, and co-author Nora Becker of Boston University propose requiring doctors to fill out a prior authorization form explaining their rationale for prescribing the antiparasitic drug. The authors acknowledge that this will create a hurdle for patients who need ivermectin for FDA approval to treat worms, head lice and some skin conditions, but the impact will be far less than those receiving the drug for COVID-19.

“Our view is simple, insurance companies should not cover these prescription drugs unless ivermectin is proven to be an effective treatment for COVID-19,” Chua said.

Eric Musser, director of federal affairs for the National Council for Quality Assurance, a nonprofit that provides accreditation and performance metrics to physicians, health plans and medical groups, said they take the FDA’s recommendations “very seriously.”

“Anything we might include in our standard of care for COVID or other illnesses will depend on the facts,” he said.