Oklahoma doctor Matthew Payne regularly encounters covid-19 patients in the hospital who say they had feared coronavirus vaccines and thought they had found a safer approach - taking ivermectin, a medicine long used to kill parasites in animals and humans.
"There is surprise and shock when they initially get sick and have to come to the hospital," said Payne, a hospitalist at Stillwater Medical Center. "They'll say, 'I'm not sure why I feel so bad. I was taking the ivermectin,' and I will say, 'It doesn't do any good.'"
Doctors and public health officials say they have spent the pandemic fighting rampant misinformation on top of a deadly virus, but the ivermectin craze is one of their strangest battles yet. Promoted by conservative talk show hosts, politicians and even some physicians as an effective treatment for covid-19, the medication has soared in popularity this year despite having no proven anti-viral benefits - and also some clear harms when abused. Prescriptions of the anti-parasitic medication, used to treat river blindness and intestinal roundworms in people, have spiked during the pandemic and especially this summer, jumping from an average of 3,600 weekly prescriptions in the year before the pandemic, to more than 88,000 in one week in August, according to the Centers for Disease Control and Prevention.
Health departments are warning of spikes in ivermectin poisoning and hospitalizations as people snap up feed store products meant for large animals. "You are not a horse," the Food and Drug Administration felt compelled to declare last month. "You are not a cow. Seriously, y'all. Stop it." The agency has not approved ivermectin to treat or prevent covid-19 and urged against that use in a recent public advisory, warning that "taking large doses of this drug is dangerous" and potentially fatal.
Experts worry the enthusiasm for the deworming medicine is muddying urgent messaging about the only proven way to protect against severe cases of covid-19 - vaccines that were determined to be safe and effective after large, randomized clinical trials, and given to more than 170 million people in the United States. Many officials despair of the embrace of unproven approaches such as ivermectin and vitamin cocktails over vaccines as a symptom of a broader problem: a public health crisis made worse by many people's distrust of medical authorities while they rely on often-faulty information from some of the country's most influential people, which is amplified through social media.
"When people get fixated on inappropriate recommendations, then they unfortunately don't get vaccinated," said Hawaii Lt. Gov. Josh Green, a Democrat and an emergency room doctor who blames conservative media for fanning unfounded hopes about ivermectin. "They don't do the things that will actually help."
Calls about ivermectin exposure to poison control centers on the country jumped to five times normal levels in July, according to data from the American Association of Poison Control Centers. About a third of nearly 1,200 calls so far this year involved people referred for medical treatment, and about 8% were ultimately admitted to the hospital, said Alvin Bronstein, who leads the association's national data system. The share of people admitted to the critical care unit more than quadrupled compared with the same period last year.
A CDC alert to clinicians last week said that one person who drank cattle ivermectin to prevent coronavirus infection was hospitalized for nine days, with symptoms including hallucinations and tremors. Another person who misused ivermectin this year died, according to Bronstein, who said he does not have information on what form of the drug the person took and cannot say why.
Interest in ivermectin as a possible coronavirus treatment was spurred last spring by an Australian study that found it killed the virus in the lab. The cheap and widely available drug - deemed an "essential medicine" by the World Health Organization - has treated parasites in humans and animals for decades so effectively that two scientists won the 2015 Nobel Prize in physiology or medicine for their work on it.
Despite the Australian finding, many scientists doubted that humans could take high enough doses to replicate the effects seen in a lab, and even the researchers behind the study advise against using the drug as a covid-19 treatment outside of clinical trials. But prescriptions skyrocketed in poorer countries last summer, especially in Latin America, as "the medical community took the one-size-fits-all attitude" based on the drug's price and good safety record, one Brazilian researcher observed.
In the United States, a small but vocal group of doctors called the Front Line COVID-19 Critical Care Alliance has sought to make ivermectin a routine part of both covid-19 prevention and treatment. One founder, Pierre Kory, claimed late last year in testimony to the Senate Homeland Security Committee that new research gave "conclusive data on the profound efficacy" of ivermectin as an intervention at "all stages" of covid-19.
Federal health agencies were not swayed. Noting mixed evidence and problems with the existing studies after a presentation from Kory and his colleagues, a National Institutes of Health committee stopped recommending against the drug as a covid-19 treatment, but said there was "insufficient data" to endorse it.
Although dozens of studies on ivermectin are ongoing - including a large randomized trial of repurposed drugs supported by NIH - one group of researchers who reviewed data from 14 ivermectin studies found that the results so far "cannot confirm the widely advertised benefits." Two authors of the review, Maria Popp and Stephanie Weibel of Germany's University Hospital of Würzburg, told The Washington Post that they recommend against using ivermectin for covid-19 given the lack of evidence, noting that "every drug has side effects."
George Rutherford, a professor of epidemiology and biostatistics at the University of California, San Francisco, spoke with more certainty: "This is a drug that does not work," he said, comparing those pushing ivermectin as a coronavirus treatment to "19th-century snake-oil salesmen."
Payne, the Oklahoma hospitalist, said he worries many people are being encouraged to take ivermectin as a "suitable alternative" to vaccination. At one point this summer, he said, about a quarter of his patients arriving at Stillwater Medical Center with covid-19 had been taking the medication. The lack of evidence that ivermectin protects against the coronavirus is a common topic in his evening calls with the families of severely ill covid-19 patients.
"It's a battle with patients and family members to explain why it's not recommended to do this," he said.
The Federation of State Medical Boards warned in July that doctors who spread falsehoods about coronavirus vaccines could have their medical licenses revoked or suspended, but did not address treatments. Few doctors have been publicly disciplined for promoting misinformation during the pandemic.
The Arkansas State Medical Board said last month that it is investigating a physician after he came under fire for routinely prescribing ivermectin to jail inmates as a coronavirus treatment and prevention measure. But such a probe is complicated by the fact that ivermectin is an approved anti-parasite drug, and doctors often prescribe drugs approved for one purpose for other things. "In general there are no direct repercussions for off-label usage," Payne said.
Doctors who espouse ivermectin to treat covid-19 deny they are undermining immunization efforts, saying they advocate many strategies at once. But "the role of vaccination" is a small footnote in the Front Line COVID-19 Critical Care Alliance's posted protocol for covid-19 prevention, which says ivermectin, vitamins and other substances can provide a "safety net for those who cannot or have not been vaccinated."
Another founding member of the Alliance, Ohio physician Fred Wagshul, said that about a quarter of his hundreds of patients taking ivermectin are using it in lieu of vaccines. The pulmonologist said he recommends immunization, but he also insists - falsely - that the deworming drug is known to give even better protection than the shots.
Joseph Varon, an Alliance member and chief of critical care at United Memorial Medical Center in Houston, said he is dismayed to see people applauding his use of ivermectin on social media, while railing against vaccines. He defended his and other doctors' off-label prescriptions as necessary in a crisis. "We started trying things because, you know, people were dying," said Varon.
Even scientists pursuing trials on the efficacy of ivermectin say the existing studies are too small or flawed to draw conclusions.
The data is "not particularly favorable at this point," said David Boulware, an infectious-disease specialist at the University of Minnesota Medical School working on one clinical trial. He pointed to another randomized trial in Brazil that recently reported no benefits from ivermectin as larger and thus more compelling than past efforts, and said his trial may simply provide more definitive evidence of the same thing.
Boulware experienced the intensity of the discussion around ivermectin when people started accusing him of denying study participants a lifesaving medicine by giving some a placebo - part of any randomized trial, which is considered the gold standard approach to determine whether treatments are effective. "Are you a reembodied NAZI Josef Mengele?" he said one email read.
"Ivermectin is rapidly becoming very polarized, just as hydroxychloroquine did," Boulware said, referring to the anti-malarial drug that former president Donald Trump promoted as a cure for covid-19 and that randomized trials found ineffective.
"There's either people that believe it totally is a cure-all and works or . . . it's highly dangerous," Boulware said of ivermectin. "And the reality is neither extreme is true."
Ivermectin has gained particular traction in conservative circles alongside accusations that the government and the drug industry are stifling discussion about the medication.
Sen. Rand Paul, R-Ky., told a crowd last week that "hatred for Trump" was preventing objective study of both ivermectin and hydroxychloroquine. Rep. Louie Gohmert, R-Texas, promoted ivermectin at a Friday speech while casting doubt on the safety of vaccines. Ralph Lorigo, the Erie County Conservative Party chairman, has successfully sued in New York, Illinois and Ohio to force hospitals to provide ivermectin for covid-19 patients.
Fox News hosts such as Laura Ingraham and Tucker Carlson have also promoted the drug to large audiences, even as they sow skepticism of coronavirus vaccines as "experimental." Carlson, who hosts the most-watched show on cable television, declared falsely last month that the vaccines "do not work" and in late June featured podcaster and former biology professor Bret Weinstein, an advocate of deploying ivermectin against the coronavirus.
Fox News pointed The Post toward shows on which various hosts and guests have praised vaccines, including Carlson's statements in late July that "there may well be profound benefits." The network also noted Ingraham's discussion of the FDA's warnings about ivermectin.
For some already distrustful of the government's coronavirus response, state and federal health agencies' latest alerts matter little.
Lisa VanNatta, a 61-year-old Texas rancher, maintained that the animal medicine is safe in the small doses she said she's been taking monthly. Many others at the county Republican Club, where she is president, are using the drug in some form, she said.
"They're taking jiggers of it, drinking it," VanNatta said of the people getting sick from ivermectin. "There's always going to be some form of stupidity."
VanNatta said she is still avoiding a coronavirus vaccine and cites videos circulating on Facebook in which a veterinarian falsely claims that mass vaccination will help create dangerous virus variants.
In Louisiana, 33-year-old Kortney Asevedo said she also fears the long-term effects of the vaccines, even after her unvaccinated mother died while sick with covid-19 and taking everything that doctors prescribed, including ivermectin.
"Me and my mom are kind of the same," she said. "We wanted to wait and just kind of see."
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The Washington Post's Ben Guarino and Lena H. Sun contributed to this report.