2020 is haunting us, and hantavirus is the séance

A hantavirus outbreak, a cruise ship, and the tightrope we are all trying to walk

If you have been online this week, you have probably know there is a hantavirus outbreak on a cruise ship in the Atlantic. You may have also noticed that the people you usually trust to make sense of public health news are getting hammered in the comments for being either too alarmist or too reassuring, sometimes by the same people, often within the same hour.

I had been doing science communication for years before the COVID pandemic, but only in classrooms, at conferences, and on private social media accounts where my audience was friends and colleagues. In March 2020, I started doing it for the general public, and in August 2020, I formally launched Unbiased Science as an LLC and podcast. Which means I came up professionally as a public-facing science communicator in the most fraught communication environment of my lifetime (so far). The post-COVID critique of public health communication is loud, sustained, and not entirely wrong. People felt whiplashed by mask guidance. They felt patronized by “two weeks to flatten the curve.” They felt lied to when “low risk” gave way to “everyone is going to get it.” Some of those critiques are legitimate. Some are bad-faith revisionism. Most are somewhere in between, but the nuance adds up.

Those of us who work in the scientific communication space are now navigating conversations about an emerging outbreak in an environment where trust in institutions, information, and each other has taken a major hit in the wake of COVID. As we continue to build a new landscape of trust, the context shapes everything about how we communicate about hantavirus. What is happening this week is a real-time test case in what we have actually learned and where we are still not gaining the trust of people who want answers.

A status check as of May 7 (around 2 p.m. EST)

The MV Hondius, an adventure expedition cruise ship, left Argentina on April 1st. This expedition cruise is the site of a hantavirus cluster confirmed by the WHO to be caused by Andes virus, a specific species of hantavirus (we’ll circle back later on why this matters). As of yesterday evening, there are 5 confirmed and 3 suspected cases, including 3 deaths, and one patient in the ICU. None of the cases are U.S. citizens. The ship is en route to Tenerife in the Canary Islands, where non-Spanish passengers will be repatriated, and Spanish nationals will be quarantined at a military hospital in Madrid.

Expedition cruises are very different than a wild Disney cruise, where you bring the whole family on. The purpose of these cruises is to take people to hard-to-reach places, which requires a smaller ship, and thus there are fewer passengers. On a traditional cruise, you’re likely there for the on-ship amenities—the pools, the activities, the food. On expedition cruises, getting off the ship to explore the places you travel to is the amenity.

There were 149 people on board in total, 7 of whom were American. Twenty-six passengers disembarked at St. Helena on April 24th as part of planned departures, including the Americans who returned to the U.S. Public health departments in California, Arizona, Virginia, Texas, and Georgia have publicly confirmed they are monitoring those individuals; none have been reported ill. The CDC has activated its Emergency Operations Center and is coordinating with state and local jurisdictions through EpiX. WHO held a media briefing yesterday morning, emphasizing that this situation is being actively contained and, in their words, “very, very different to COVID and very different to influenza.” The European Centre for Disease Prevention and Control (ECDC) also activated a Task Force on May 6th—their threat assessment continues to remain low to the general public.

For a fuller picture, my colleagues and I at The Evidence Collective are publishing a detailed brief (coming soon) on Substack.

Why this is not COVID

Andes virus is not novel. We have known about it since the 1990s. There have been documented outbreaks before, most notably in Argentina in 2018-2019, and they were contained with conventional public health tools. It is the only hantavirus with documented person-to-person transmission, but that transmission is inefficient and requires prolonged, close contact with someone who is symptomatic: sharing a cabin, sharing food, caregiving (hours of physical proximity). There is no evidence of asymptomatic or presymptomatic transmission. The incubation period is long, typically 2 to 4 weeks, with a median of around 18 days for Andes virus specifically. In an outbreak with a defined exposed cohort, like this cruise, those features make contact tracing and containment tractable in ways they were not with COVID.

Compare that to early SARS-CoV-2: a novel coronavirus we had no tools or immunity against, with efficient airborne transmission and contagiousness before symptoms appeared. By the time anyone knew they were sick, they had been spreading the virus for days and had already seeded it across the global travel network. The pandemic potential of COVID was high precisely because the things that made it impossible to contain are the things hantavirus does not have.

None of which is to say hantavirus is mild. It is a serious illness with a high case fatality rate, and early recognition matters enormously for the individuals who contract it. A high case fatality rate actually makes pathogens like hantavirus less likely to cause a pandemic. When many people are hospitalized, severely ill, or die, they are less likely to be out exposing others. The argument here is about population-level pandemic potential, not individual severity.

Not all viruses are the same. They have wildly different characteristics, and it’s those unique characteristics that dictate our public health response. Treating every emerging outbreak as if it has the same potential as COVID is an oversimplification. When people say “the U.S. risk is low,” they are not handwaving. They are interpreting the known biology of the virus.

The harder problem

You can be technically correct and still communicate poorly. Several of my Evidence Collective colleagues have posted careful, evidence-based content this week, saying the risk to the general public is low and there is no need to panic. The pushback in the comments has been intense, and a meaningful share of it comes from people who would normally consider themselves aligned with the science.

Part of what is happening is a misreading of what we are actually saying. “Don’t panic” is not the same as “We are not worried at all.” “The U.S. risk is low” is not the same as “This does not matter.” It is possible to be measured and concerned simultaneously, and that is what a calibrated public health response looks like. For some readers, “low risk” reads as “do nothing”; what they actually want to hear is “low risk and public health is working hard to keep it that way.” A small distinction that turns out to be the whole game.

But the pushback is not just a misread. There are real reasons people are reaching for it.

First, COVID. People who lived through 2019-20 watched authorities declare the virus “low risk” even as a pandemic was already quietly brewing. That memory is doing a lot of work right now, even when it is not consciously articulated. “Low risk” lands differently in 2026 than it did in 2019. You cannot say those words and not invoke the ghost of every reassurance that turned out to be premature. And it is not just the reassurances. The old ghosts have all come back this week. Ivermectin is making the rounds again as a hantavirus “treatment.” Vitamin D and zinc are right behind it. The same misinformation playbook from 2020, dusted off and redeployed for a virus most people had barely thought about until seventy-two hours ago. To be crystal clear, none of these are known to treat hantavirus.

Second, the federal trust environment is in tatters. The current administration has done significant damage to federal public health infrastructure, and many people have lost faith that the institutions designed to handle such crises are still capable of doing so. There are legitimate reasons to be concerned: leading infectious disease experts have publicly noted that the CDC has not deployed a team to the outbreak area, has not issued a Health Alert Network message to the medical community, and has been notably absent from public-facing communication about this outbreak. The U.S. withdrew from the WHO in January, severing the formal channels through which the CDC would normally be looped into an international outbreak response. The State Department, not the CDC, is reportedly leading the U.S. response. That is not normal.

An important caveat: The absence of public-facing communication is not the same as the absence of work. Even with the political demolition at the CDC’s leadership level, there are still extraordinary people working at every level of government, federal included, who are taking this seriously. State epidemiologists, public health labs, the frontline staff doing contact tracing for the disembarked passengers, and the career scientists who activated the Emergency Operations Center. The dysfunction at the top is real, and so is the work being done underneath it. The communication gap is one of the most visible casualties of the political demolition; much of the work itself continues quietly in the background. One side effect of that gap is that falsehoods fill it. A clear example this week: claims that the CDC’s Vessel Sanitation Program (VSP) was “gutted” to 12 officers. Per the CDC, VSP was designed to have only 12 staff, and the one or two civilian employees who were lost have since been reinstated (in June 2025). They are responsible for cruise ships that dock in the U.S., so this isn’t even relevant to the current discussion since the MV Hondius has not been in U.S. waters. All of this is to say that the vacuum at the top is real; the conclusions people draw about what that vacuum means are sometimes wrong.

On the what-ifs

I see this whole moment as a test. Did we actually learn from the COVID communication problem? Can we stay true to the nuance, to the evolving nature of an outbreak, while acknowledging the worst-case scenarios but staying grounded in the reality that this is nowhere near pandemic potential—all while rebuilding public trust?

Because here is the thing people seem to assume we are not doing: walking through the what-ifs. We are. Painstakingly. The Evidence Collective group chat over the past 48 hours has been a constant exercise in pressure-testing every assumption, every new piece of data, every plausible alternative scenario. What if the asymptomatic transmission data turns out to be wrong? What if the incubation period is longer than reported? What if a passenger we have not tracked yet seeds a secondary cluster? We are running those scenarios. We are reading the case reports. We are reading the NEJM literature on the 2018 outbreak. We are watching for the data that would change our assessment. And we are open to changing our assessment if the data warrant a change.

What we are also doing, because we are pragmatists, is weighing those scenarios by likelihood. That is the part that often gets lost in public-facing communication. Considering a worst case is not the same as predicting one. The question is never “is X possible?” It is “given what this virus actually does, how probable is X?” If we treated every theoretically possible scenario as equally probable, we would never leave the house. That is not vigilance, it’s fear-mongering—and that is immobilizing.

Not everyone needs to or should be present for every worst-case scenario we run. In fact, walking through every doomsday possibility in public communication or on social media doesn’t build trust; it just generates panic. But people do need to know that those with skill and expertise are rigorously pressure-testing those scenarios on their behalf. That is the trust signal that is missing for some people right now. Good communication in a crisis is not a tour of everything that could possibly go wrong. It says, “Here’s how seriously we are taking this, here is what we are doing about it, here is your risk today, and here is what you should watch for that would tell you the situation has changed.” Giving people clear criteria for reassessment is what makes “low risk” messaging resonate without feeling dismissed.

The actual tightrope

I keep coming back to a formula from the risk communication literature: risk perception is roughly outrage multiplied by hazard. Even when the hazard is really low, if outrage is high, communication has to be careful, generous, and mindful of why people are feeling what they are. The outrage exists for a reason, and dismissing it as irrational does not reduce it, but it severs the opportunity to build trust and connection.

That is the tightrope. Be honest about how bounded the risk is, without sounding like you are dismissing the fear. Validate that this feels eerily familiar, without conceding ground that the situations are actually analogous. Push back on misinformation, without becoming the person who lectures and loses the audience entirely. And continue to acknowledge that the situation is happening in real time, and new information can change how we continue to communicate.

I am so grateful that I am not navigating it alone. My Unbiased Science team members, and colleagues at The Evidence Collective, have been on group chats and Google Docs and live WHO briefings together for the past 48 hours, working out in real time how to balance nuance against detail, calm against urgency, technical accuracy against the very real and very valid fears people are bringing to the conversation. None of us are getting it perfectly right. All of us are trying. Watching these groups work is the most hopeful thing I have to point to right now.

---

Where I land

The current outbreak is serious for the people on that ship and their families. It is being contained through standard public health measures that have worked in prior Andes virus outbreaks and that are working now. At this time, the U.S. risk is low, and that assessment is not in tension with the fact that public health officials are working hard to keep it that way. Both things are true.

This is not a pandemic. It is a contained outbreak being managed in real time, under conditions of broken trust, fresh trauma, and institutional uncertainty. That is the actual challenge, and the work is in being honest about it rather than pretending the science alone is enough. But it is also a moment when science communication has the chance to do something it is often blamed for not doing: meet the public where they are. We have seen what oversimplified, top-down messaging does to trust. We have lived through the consequences. This time, with this outbreak, we know what is at stake—and we know what the alternative looks like.

I will keep updating as the situation evolves. In the meantime, give the people doing this work some grace. We are all reading the same data, taking the same hits in the comments, and trying very hard to land in the right place at the right time.

Stay Curious,