- Health
Hantavirus outbreak reignites COVID misinformation tropes
Global headlines about the MV Hondius hantavirus outbreak were accompanied by an all-too-familiar pattern emerging on social media platforms. Users posted wild speculations and conspiracy theories about the outbreak, sprinkled with generous doses of misinformation about unproven cures and vaccines—common refrains from the COVID pandemic. Below, we discuss some of the inaccurate and misleading claims spotted on social media over the past week.
Unsubstantiated claim: the hantavirus outbreak was planned/is a hoax
A callback to the conspiracy theory that the COVID pandemic was planned or fake. This theory was popular among COVID contrarians and “medical freedom” activists, as it justified their opposition to public health measures to combat COVID, such as mask-wearing, vaccination, and lockdowns. Conspiracy theorists advanced all sorts of information that allegedly supported their claims, ranging from the mere existence of pandemic preparedness exercises and patents to (mis)understandings of how PCR tests work.
None of these claims stand up to scrutiny, but that hasn’t stopped some from pushing the same conspiracy about the hantavirus outbreak. However, this conspiracy theory doesn’t make sense in light of the facts, which favor the hypothesis of a naturally occurring zoonosis as the origin of the outbreak.
For starters, hantavirus isn’t new (it was first discovered in the 1970s) and the type that caused the outbreak on the MV Hondius, called the Andes virus, was first found in the 1990s and therefore has been known to scientists for many years.
Furthermore, hantavirus naturally circulates in multiple regions of the world, including Asia, Europe, and the Americas. Outbreaks, including those caused by the Andes virus, have spontaneously occurred on several occasions in the past[1-3], although these perhaps did not achieve the same international media coverage that the MV Hondius outbreak did. The media attention accorded to the MV Hondius outbreak may therefore contribute to the perception that the outbreak is something novel, when it is simply the latest one in a long line of others.
In addition, complete genome sequencing of a sample from a hantavirus patient who’d been on the MV Hondius suggests that the virus responsible for the outbreak is that of a naturally circulating Andes virus found in rodents in Chile and Argentina.
In light of the fact that the MV Hondius departed from Ushuaia, Argentina, and that some of its passengers had spent time visiting the region before boarding the ship, the hypothesis that the outbreak started as a result of zoonotic transmission (for instance, a passenger getting exposed to a rodent carrier of the virus while traveling in the region and thus getting infected) becomes a likely explanation. This is also reinforced by the fact that zoonotic transmission of infectious diseases is quite common: the World Health Organization estimates that around 60% of emerging infectious diseases reported globally come from zoonoses.
The bottom line: historical and scientific evidence show that the outbreak is most likely the result of a naturally occurring zoonotic transmission, rather than the product of human intervention and nefarious plots. But spinning a web of conspiracies is more rewarding on social media, as they attract far more clicks and engagements that can be monetized.
Unsubstantiated claim: ivermectin is effective against hantavirus
Social media accounts known for flogging ivermectin as a COVID cure recently turned to promoting it for hantavirus. Take for example this post on X by otolaryngologist Mary Talley Bowden, in which she claimed that “ivermectin should work against” hantavirus, citing the drug’s ability to block viral replication by acting on the nucleus. Bowden’s post received a boost from former US Congresswoman Marjorie Taylor Greene, who reposted it.
Science Feedback reviewed the claim here and found that the mechanism described by Bowden wouldn’t work in the case of hantavirus infection. While some in vitro studies did find that ivermectin could block the entry of viral proteins into the host cell’s nucleus, hantavirus does not rely on this process to replicate.
Inaccurate claim: Pfizer document shows hantavirus is a side effect of the COVID vaccine
Adverse event reports have been weaponized by anti-vaxxers for years and the hantavirus outbreak presents as good an opportunity as any to brandish these reports again. In a recent iteration of this tactic, social media posts on X and TikTok claimed that a Pfizer document showed hantavirus infection as a COVID vaccine side effect.
This is misleading. A Reuters fact-check explained that the adverse events listed in the document involved any medical event experienced by a person after vaccination, regardless of whether the vaccine caused the event. No credible evidence causally links hantavirus infection to COVID vaccination.
lacks context: 98% of participants in hantavirus vaccine clinical trial suffered adverse events
Anti-vaxxers have wasted no time preparing the ground for vaccine misinformation, as this post from Nicolas Hulscher on X demonstrates. The claim is based on this study published in 2023, led by researchers at the University of Cincinnati and the U.S. Army Medical Research Institute of Infectious Diseases[4]. It looked at the safety and immunogenicity (the ability of the vaccine to stimulate a protective immune response) of a vaccine candidate against the Andes virus.
The study reported the results of a Phase I placebo-controlled clinical trial in 48 healthy adults. While it did report that 98% of participants experienced a local adverse event, it also clarified that most were mild or moderate, and none were serious. Examples of reported adverse events included common reactions such as swelling, tenderness, local pain, headache, and fatigue. The researchers concluded that “This first-in-human candidate HPS vaccine trial demonstrated that an ANDV DNA vaccine was safe and induced a robust, durable immune response”.
Audiences “primed to distrust public health guidance before it even arrives”
Many of the accounts that engage in the spreading of hantavirus misinformation aren’t new, having built up large audiences receptive to their messages during the COVID pandemic. This might explain the speed with which misinformation about hantavirus traveled.
Experts have stated that the hantavirus outbreak is not a pandemic-level threat unlike COVID, citing its slower incubation and different transmission dynamics. Therefore, the immediate harm caused by misinformation about the outbreak is likely to be relatively small and limited.
But in the long run, what these social media reactions portend for public health responses in future pandemics is sobering. In an article for STAT News, epidemiologist Katrine Wallace highlighted how the narratives around disease outbreaks are now “prewritten” and audiences are primed to receive cues that lead them down a rabbit hole of health misinformation. When the few sources of credible information on social media are drowned out by a chorus of false claims, distrust of public health guidance may eventually become the norm, rather than the exception.
References
- Padula et al. (1998) Hantavirus Pulmonary Syndrome Outbreak in Argentina: Molecular Evidence for Person-to-Person Transmission of Andes Virus. Virology.
- Bayard et al. (2004) Outbreak of Hantavirus Pulmonary Syndrome, Los Santos, Panama, 1999–2000. Emerging Infectious Diseases.
- Martínez et al. (2020) “Super-Spreaders” and Person-to-Person Transmission of Andes Virus in Argentina. New England Journal of Medicine.
- Paulsen et al. (2023) Safety and Immunogenicity of an Andes Virus DNA Vaccine by Needle-Free Injection: A Randomized, Controlled Phase 1 Study. Journal of Infectious Diseases.
