How Is Hantavirus Similar to (And Different From) COVID-19? Experts Explain

Reported by Women's Health Magazine.

Hantavirus took over social media this week after the WHO reported on May 4 that three people died from an outbreak aboard a cruise ship in the Atlantic Ocean — and the collective anxiety was instant. The comparisons to early COVID were inevitable. But according to Women's Health Magazine, experts are urging calm, and the science actually backs them up.

Here's what's circulating: the strain identified on the ship is the Andes virus, a form of New World hantavirus found in the Americas. Unlike most hantaviruses — which spread only through contact with rodent droppings, urine, or feces — the Andes strain is the sole documented type capable of human-to-human transmission, passing through aerosolized respiratory and saliva droplets. That detail alone is enough to send anyone spiraling. But transmission potential is measurably limited. Thomas Russo, MD, professor and chief of infectious disease at the University at Buffalo, points out that during one previous outbreak, the reproductive number (R0 — the average number of people one infected person passes the virus to) clocked in around two, then dropped below one once basic infection control was introduced. "Below one means it's not transmissible to other individuals," Russo explains. Compare that to COVID's omicron variant, which hit an R0 of roughly five. The two aren't in the same category.

The Numbers Are Scary — Until You Read Them Correctly

The mortality rate for Hantavirus Pulmonary Syndrome is estimated between 30 and 40 percent for those who develop cardiopulmonary complications — significantly higher than COVID's general rate of under one percent. That gap sounds alarming, but context matters: the CDC recorded only 890 U.S. cases of the disease from its identification in 1993 through the end of 2023. The mortality figures also likely overestimate true risk because asymptomatic cases go uncounted. Overlapping symptoms — fever, muscle aches, shortness of breath — exist because both viruses attack the respiratory system, though through different mechanisms. Severity ranges widely for both, and Russo suspects some people in this outbreak will show minimal or no symptoms at all.

As for containment: exposed passengers from the cruise ship are currently being isolated and monitored at the University of Nebraska and Emory University, two facilities Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security, describes as "state-of-the-art." Critically, there are zero confirmed secondary cases. "We've got a pretty good handle on who's been exposed and who's infected," says Russo. Adalja is direct: "I don't think hantavirus is going to amount to any threat to the general public. Hantavirus is a more forgiving virus than COVID." Both experts do flag a real concern — the CDC is understaffed and has lost key subject matter experts — but they believe current outbreak protocols are functioning.

There's one genuinely optimistic data point buried in all this: mRNA vaccine technology, fast-tracked during COVID after three decades of foundational research, has permanently changed pandemic preparedness. "The ability to develop a hantavirus vaccine would be greatly expedited by the availability of mRNA technology," Russo says. We are not where we were in 2019 — and that distinction is worth holding onto.

The takeaway: hantavirus is worth monitoring, not catastrophizing — the science, the containment infrastructure, and the absence of secondary cases all point toward a self-limited outbreak, not a rerun.

Read the original at Women's Health Magazine.