Hantavirus Outbreak Revives COVID-Era False Health Claims

Highlights

A hantavirus outbreak linked to a Dutch cruise ship in early May was followed by false health claims that mirror patterns documented in previous outbreaks, including unsupported claims that ivermectin is an effective treatment, that the outbreak was planned in advance, and that it was caused by COVID-19 vaccines.

The Monitor also examines a new analysis of Americans’ relationship with health and wellness influencers, finding that most who get health information and advice from them express skepticism about what they hear.

What We’re Watching

As Hantavirus Cases Emerged, So Did Familiar False Claims About Causes and Cures

False health claims tend to follow recognizable patterns across outbreaks, including distrust of official sources, promotion of unproven treatments, and accusations of hidden profit motives. The hantavirus outbreak linked to the Dutch cruise ship MV Hondius was no exception, with several familiar false narratives spreading alongside the official response from the World Health Organization (WHO) and other agencies:

• Unproven Treatments: Within hours of the first headlines, a Texas otolaryngologist who became a prominent promoter of ivermectin during COVID-19 posted without evidence on May 6 that ivermectin “should work” as a hantavirus treatment because it “is a RNA virus,” claiming that ivermectin “blocks RNA viruses” from replicating in the cell nucleus. The claim overstates available evidence from some laboratory and animal studies about ivermectin’s effect on virus replication. There is no evidence that ivermectin would be effective against hantavirus, which replicates outside of the nucleus, and there is no approved vaccine or antiviral treatment for hantavirus. Former U.S. Representative Marjorie Taylor Greene shared the post, recommending ivermectin, vitamin D, and zinc to her followers as potential hantavirus treatments. The following day, the same physician offered that she would sell ivermectin without a prescription to her followers in Texas.
• False Claims that the Outbreak Was Caused by COVID-19 Vaccines: A Pfizer document listing adverse events that had been monitored during COVID-19 vaccine trials was also misrepresented as evidence that the vaccines caused hantavirus, a claim that was also made about COVID-19 itself. The document listed conditions that researchers designated in advance as worth monitoring closely during trials, not events that were observed or confirmed to have occurred. Hantavirus pulmonary infection appeared on that list, but its inclusion reflects standard safety surveillance, not causation.
• The “Plandemic” Narrative: While less widespread than other false health claims about the outbreak, some social media accounts framed the outbreak as a “plandemic” and evidence of a depopulation campaign, reviving narratives that circulated during COVID-19. Their posts misleadingly presented early-stage research into a potential hantavirus vaccine, announced in 2024, as proof that the outbreak was planned in advance and referred to potential vaccines as dangerous or as primarily vehicles for pharmaceutical companies to profit. In reality, research into hantavirus vaccines has been ongoing for decades because it is a known pathogen with no available vaccines.

Why This Matters: The narratives that accompanied the hantavirus outbreak are not new. Researchers and fact-checkers have documented nearly identical claims in response to COVID-19, mpox, and avian flu, often with the same accounts recycling framing across new outbreaks. Each cycle may make it harder for accurate health information to reach audiences before these false narratives spread.

Most Americans Who Follow Health Influencers Are Skeptical of What They Hear

A new Pew Research Center analysis offers a detailed look at who is producing and consuming health and wellness content on social media. Four in ten U.S. adults, and half of those under 50, say they ever get health and wellness information from social media influencers or podcasts. Yet among those audiences, trust is limited. Just one in ten say they trust all or most of what they hear from these sources, while nearly a quarter (24%) say they trust not too much or none of it. The majority, about two-thirds, say they trust some. While most (54%) say the information has helped them better understand how to be healthy, about one in eight (12%) say it has left them more confused.

Of the nearly 7,000 health and wellness influencers Pew identified on YouTube, TikTok, and Instagram, about 41% describe themselves as some kind of health care professional, a category that includes not only physicians and nurses but also chiropractors, naturopaths, and functional medicine practitioners. The remaining health and wellness influencers describe themselves as coaches, entrepreneurs, or offer little biographical information at all. Most people who get content from influencers say they come across this content passively rather than seeking it out. Certain groups, including Black, Hispanic, and Asian Americans, and those without health insurance, are more likely to turn to health influencers for information, a finding that may point to gaps in the formal health care system as a driver of influencer engagement.

The findings add context to KFF polling, which found that 55% of the public use social media to find health information or advice at least occasionally, and 14% report getting health advice regularly from social media influencers. But trust in influencers was limited in the KFF survey as well: about four in ten (39%) of those who regularly got health information or advice from influencers said those influencers were primarily motivated by serving the public interest, compared to six in ten (61%) who said they were primarily motivated by their own financial interests. As KFF President and CEO Drew Altman wrote in a “Beyond the Data” column last August, the relatively small share of people who say they regularly get health information from influencers suggests that health communicators should keep the role of influencers in perspective, at least for now.

A Closer Look at the State Level: Nearly Half of California Residents Distrust the Health Care System, But Most Trust Providers

As the 2026 midterms approach, health information and trust dynamics vary across states, shaped by local politics, demographics, and access. The Monitor will periodically examine state-specific data and trends as part of our broader tracking of the health information environment.

A survey of California residents conducted by NORC at the University of Chicago for the California Health Care Foundation (CHCF) found that 46% say they have “not much” trust in the health care system or “none at all.” But, trust varies sharply depending on who within the system is being evaluated. Nine in ten Californians say they trust nurses and more than eight in ten say they trust their personal doctor, while fewer than half (49%) trust hospital administrators and roughly a third trust health insurance companies (33%) or pharmaceutical companies (30%). The survey also found that Californians who had skipped care due to cost were significantly less likely to trust the system overall, with 35% of that group expressing at least a fair amount of trust, compared to 54% of Californians overall.

These findings are in line with past KFF polling showing that doctors and health care providers are consistently the public’s most trusted source of health information. More recently, KFF’s latest April Health Tracking Poll finds that most of the public (70%) say they trust doctors and health care providers at least “a fair amount” to act in the public’s best interest, a sentiment that is shared across partisanship.

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