Within days of reports of a rare Andes hantavirus outbreak, political figures and prominent Covid-era ivermectin advocates once again began promoting the drug as a potential treatment — even as infectious disease experts say there is no clinical evidence supporting its use against hantaviruses.
Former congresswoman Marjorie Taylor Greene posted on X on Wednesday suggesting vitamin D, zinc, and ivermectin could prevent the rodent-borne disease. Ivermectin, an antiparasitic medication, surged in popularity during the Covid-19 pandemic as vaccine skepticism rose. In another post, Greene shared a 2024 article about mRNA hantavirus vaccine research while claiming pharmaceutical companies “manipulate the virus (bioweapon)” and “make the vaccine (poison).”
Other high-profile ivermectin advocates also circulated claims online, including physician and activist Mary Talley Bowden, whose post about ivermectin and hantavirus was viewed millions of times on X, and commentator Josh Walkos, known online as “Champagne Joshi,” who shared posts questioning hantavirus vaccine development.
“There is zero evidence indicating that ivermectin would be a treatment for any hantavirus.”
Primarily found in South America, the Andes hantavirus can cause severe respiratory illness and, unlike most hantaviruses, has demonstrated limited ability for person-to-person transmission in previous outbreaks. Health authorities are now investigating a recent cluster linked to international travelers aboard an expedition cruise ship traveling between Argentina, Antarctica, and South Africa, with several cases identified beyond the vessel.
The strain can be deadly, with mortality rates in some outbreaks estimated at as high as 50 percent. But experts say it typically requires close contact to spread, making it significantly less transmissible than Covid-19.
The resurgence of ivermectin claims comes as some Republican-led states continue efforts to expand access to the drug years after it became a flashpoint during the Covid-19 pandemic. On Wednesday, the South Carolina House passed legislation that would allow ivermectin to be sold without a prescription.
“There is no meaningful clinical evidence for ivermectin against hantavirus, full stop,” said Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security whose work focuses on emerging infectious disease, pandemic preparedness, and biosecurity.
Adalja said the only antiviral formally evaluated in clinical trials for hantavirus is ribavirin, and even those results showed limited benefit.
Vincent Racaniello, a professor of microbiology and immunology at Columbia University, said the Andes virus remains the only hantavirus known to spread person to person.
“There is zero evidence indicating that ivermectin would be a treatment for any hantavirus,” Racaniello said.
While ivermectin is approved to treat certain parasitic infections in humans, including river blindness and intestinal strongyloidiasis, the FDA warns that improper use or high doses can cause serious side effects, including seizures and neurological complications.
Racaniello warned that unsupported medical claims circulating on social media can create public confusion during disease outbreaks.
Health communication experts say distrust that emerged during the Covid-19 pandemic continues to shape how some Americans respond to new disease outbreaks. Evolving public health recommendations during the pandemic, including former National Institute of Allergy and Infectious Diseases Director Anthony Fauci’s acknowledgment that the widely used 6-foot social distancing rule was not firmly grounded in data, contributed to enduring skepticism toward public health institutions.
Even as his administration rushed vaccine development, President Donald Trump publicly promoted unproven Covid-19 treatments including hydroxychloroquine, further politicizing debates around experimental therapies and public health guidance.
The president has so far offered scant remarks on the outbreak. Asked about the virus on Thursday, he told reporters “it should be fine.”
“People’s experience with Covid-19 permanently changed how many view public health guidance,” said Rebecca Fish, a health communications professor at the University of North Carolina Hussman School of Journalism and Media who previously worked in senior health policy and pharmaceutical industry roles. “There is now a much higher level of skepticism toward institutions like the CDC and official public health messaging.”
The Department of Health and Human Services and Centers for Disease Control and Prevention did not respond to questions from The Intercept about whether federal health agencies have evaluated ivermectin for Andes hantavirus or plan to address unsupported treatment claims circulating online.
Robert F. Kennedy Jr., who has publicly defended the off-label use of ivermectin and criticized clinically informed public health policies for Covid-19, now oversees HHS and the CDC. Last year, CBS News reported that layoffs tied to Kennedy’s restructuring of federal health agencies eliminated all full-time employees in the CDC’s Vessel Sanitation Program, which investigates outbreaks aboard cruise ships. Amid the news of the hantavirus outbreak, the administration confirmed to STAT that the cuts had been reversed. The chief of the Vessel Sanitation Program, however, announced his retirement on Wednesday.
“When someone feels ridiculed for asking a reasonable question, they don’t defer to authority, they route around it.”
People in a health crisis often look for reassurance and a sense of control, not just facts, Fish said, adding that unsupported treatment claims can spread quickly online when distrust in institutions is already high.
“When someone feels ridiculed for asking a reasonable question, they don’t defer to authority, they route around it,” she said. “The question is not whether that vacuum will be filled, but by whom and with what.”
Fish said public health officials and journalists should distinguish carefully between what is false, what remains unproven, and what is still unknown as evidence develops.
But experts said distrust in public institutions does not eliminate the need for clinical evidence when evaluating medical treatments.
“Clinical claims require real evidence that goes beyond anecdotal evidence,” Adalja, the Johns Hopkins scholar, said.
Racaniello, the microbiologist, warned that unsupported medical claims circulating on social media can still carry real public health risks.
“The problem arises when people inject their opinions on social media when they have no expertise in the matter,” Racaniello said. “Ivermectin at high doses can be damaging, so encouraging its use in this outbreak is irresponsible.”
