Hantavirus: How it differs from COVID

With memories of the COVID pandemic still fresh in many people's minds, it's understandable that communities are worried about hantavirus spreading internationally.

"I know you are worried," wrote Tedros Adhanom Ghebreyesus, Director-General of the World Health Organization (WHO), in a letter to the people of Tenerife, Spain, on May 9, 2026.

The cruise ship MV Hondius — on which hantavirus spread and killed three people and infected others from April to May — was about to dock at Tenerife's Granadilla Port. 

From there, passengers and crew (total 147 people) were to be repatriated to their home countries, including Germany, France and Australia.

"I know that when you hear the word 'outbreak' and watch a ship sail toward your shores, memories surface that none of us have fully put to rest," Tedros said.

But there is a significant difference between COVID and hantavirus. 

When the SARS-CoV-2 coronavirus arose in 2019 and caused COVID, neither public health scientists nor healthcare workers had ever seen it before. No one knew what it was, how fast it would spread, how to stop or treat it. 

Hantavirus, on the other hand, has been known since 1993. 

And because it is known to cause a lung infection called Hantavirus Pulmonary Syndrome (HPS), appropriate distancing measures were put in place on the ship — once laboratory tests confirmed it had caused the first two deaths. 

An analysis of a hantavirus outbreak in Argentina in November 2018, indicates just how effectively even basic control measures, such as social distancing, slow the spread of infection from person-to-person. 

We did not have that knowledge about COVID when it started — in fact, to this day, we still don't know exactly where it started.

Analysis of the 2018-2019 Argentine hantavirus outbreak

In a paper published in 2020, researchers described how the speed of transmission of Andes virus — the same variant as that on the MV Hondius cruise ship — halved when "public health officials enforced isolation of persons with confirmed cases and self-quarantine of possible contacts" during a 2018-2019 outbreak in Argentina. 

Is the hantavirus the next pandemic?

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Control measures were enforced after authorities confirmed 18 people had been infected with Andes virus at a mass gathering.

"These measures most likely curtailed further spread," wrote the researchers in the New England Journal of Medicine. "The median reproductive number (the number of secondary cases caused by an infected person during the infectious period) was 2.12 before the control measures were enforced and decreased to 0.96 after the measures were implemented."

The situation on the MV Hondius was different. While the number of known cases — at time of writing on May 11, 2026 — is fewer at seven confirmed and two suspected cases, it did take longer for control measures to be enforced. 

After the first person died on April 11, Oceanwide Expeditions, which runs the ship, said it was May 4 — more than three weeks — before hantavirus was confirmed as the cause of death. That was two days after the WHO was notified that there was a "cluster" of infected people on the ship. 

Once the MV Hondius docked at Tenerife, however, there was no doubt about the cause of infections, and Spanish health authorities said they took "'all measures' to prevent hantavirus spreading." 

Passengers, crew, and health authorities wore face masks and personal protective suits, and personal effects were carried in sealed bags. 

"Reducing any potential contacts and the use of FFP2 [masks] for passengers and people who might come in contact with them during the procedures of disembark and transport to the country of origin are supported by what we know about this virus," said Giulia Gallo, a researcher at The Pirbright Institute, UK.

Generally, hantavirus infections are relatively uncommon globally. In 2025, the WHO documented 229 cases and 59 deaths in the Americas. There is no vaccine for the infectious disease.

Edited by: Natalie Robinson