A man goes to a birthday party, sits next to someone with hantavirus, catches it, gives it to his wife, and dies. His wife then infects 10 more people during her time. Another guest at the same birthday party has no interaction with the index patient except to say “hello” when they cross paths, but that person also becomes ill.
One index patient, 33 subsequent infections, 11 deaths, four waves of infection.
This is from a carefully recorded hantavirus outbreak in Argentina in late 2018 and early 2019, published in the journal New England Journal of Medicine (NEJM) Almost the same Andean strain of hantavirus caused the recent outbreak on the Dutch ship MV Hondius. Yet since this latest outbreak hit the news last month, public health officials have been claiming that the virus is spread through “prolonged close contact.” The evidence is not nearly as encouraging.
In any outbreak, the most important question is: How does it spread? The answer informs the guide for everything else, including how to stay safe, what safeguards to put in place, and who should be notified when monitoring communications. Get it wrong and everything else falls apart.
We made this mistake at the beginning of the coronavirus pandemic, and the cost was high. Health officials thought that the virus spread on surfaces (“formite infection”) and through large droplets that come out quickly and cannot travel six feet. That’s why we spent a year cleaning elevator buttons and putting stickers on the floor to tell people where to stop. But these measures did little to stop the spread of the disease which actually traveled through tiny particles that sat dangerously in poorly ventilated and enclosed spaces.
Now we are wrong again. “This is not a respiratory disease,” Mike Waltz, the US Ambassador to the United Nations, said about hantavirus in ABC News interview Sunday, adding, “It’s very rare to see it passed between humans.” The transmission of the virus “requires close contact,” Jay Bhattacharya, acting director of the Centers for Disease Control and Prevention, emphasized. last week. Official CDC communications have continued to emphasize that “long-term, close contact” is essential to transmission, as have other public health officials outside the Trump administration.
As an expert in what we call “exposure science,” I’ve spent my career doing scientific research to understand how diseases spread and what we should do about it. As a member of Lancet Commission on COVID-19, I chaired the Safe Work, Safe School, and Safe Travel task forces, and was an early proponent of the theory that COVID-19 spreads through space. There was early evidence of air pollution, which my colleagues and I tried to draw attention to. We illustration the early 2020 outbreak of the disease on the Diamond Princess cruise ship and found that 90 percent of the spread was aerosols, not contaminated surfaces, but the CDC didn’t update its guidance until late 2020. I’m dismayed to see such a pattern continue now.
Hantaviruses usually come from rat feces. A person cleans a dusty area that has rat droppings, inhales the particles and gets sick. It is the only Andean strain of hantavirus known to be transmitted from human to human. In the outbreak of memory in NEJMthe virus spreads without physical contact or prolonged exposure. A patient becomes ill after just crossing paths with someone who was sick. Two others have been infected while sitting at tables meters away. One person infected five others within 90 minutes at a party. The NEJM the authors suggested that the virus spreads through the air.
Although NEJM the evidence is clear, officials have kept repeating “prolonged, close contact,” so I wanted to make sure I didn’t miss anything. Last week I spoke to a doctor on board the MV Hondius as a passenger but who flew to help treat infected passengers after the ship’s official doctor fell ill and was evacuated. He told me that the original treating doctor and staff were clearly in close contact with the first patient. But the others who got sick? They had only shared space in the dining room and the lecture hall, and had no close contact. We are now at 10 confirmed cases from the ship, which is consistent with the trends of previous outbreaks: one person infecting many, no close contact required.
Every outbreak investigation involves clinical clinical trials, painstaking epidemiology, reconstructed time-activity patterns, and gene sequencing—but almost always, without fail, investigators ignore the exact location where the outbreak occurred. Was the cruise ship’s ventilation system working? What filters did it have, and were they running?
This is important because medical teams treating patients need to know how they may be exposed. When infected passengers go home for quarantine, their households need to understand the risk. When passengers fly back to their home countries, contact tracers need to know what the significance of the exposure is. A doctor who treated patients on the ship told CNN that he relied on goggles, a gown, and hand washing to protect himself. But considering that this virus is airborne, an N95 mask with a strong ventilation and filtration system would serve him well.
This outbreak is unlikely to be a pandemic, mainly because hantaviruses are less contagious than influenza, measles, and SARS-CoV-2. But given how little experience we have with this virus, any certainty is hubris. Fortunately, despite the flawed message, the system is largely working: Officials are investigating, passengers are being quarantined, critically ill patients are receiving treatment, and the risk to the public is minimal. International and national public health authorities are acting responsibly.
But what comes next depends on how well public health officials communicate what precautions people should take. If people mistakenly believe that transmission is only based on “prolonged close contact,” they may be taking a risk that they will soon regret.
Public health officials should be more honest and more humble about how this virus spreads. An important lesson from COVID is that officials should be clear about communicating that we are often learning in real time, and should avoid making bold statements that could be dangerously misleading weeks or months later. When it comes to preventing an outbreak from becoming a disaster, insisting on the wrong answer to the main question –How does it spread?– can be worse than no response at all.
