Hantavirus is very different to COVID. Here’s why the ‘Andes virus’ won’t cause the next pandemic

For many people, news of a virus outbreak on a cruise ship immediately brings back memories of COVID spreading when the Ruby Princess docked in Sydney in March 2020. Of the passengers and crew who disembarked, 575 had COVID. The virus then spread to the community.

So it’s understandable people are concerned that passengers from the MV Hondius need to be quarantined after potential exposure to Andes virus, a rodent-borne hantavirus.

However, the comparison with COVID only goes so far. Andes virus is serious and authorities are right to respond cautiously. But experts, including from the World Health Organization, note it doesn’t have the characteristics needed to become “the next COVID”.

As of May 11, European health authorities have reported nine cases linked to the cruise ship, including seven confirmed and two probable cases. Three deaths have been reported.

Five Australians and one New Zealander are being repatriated to Australia for quarantine and monitoring. The passengers will initially quarantine at the Centre for National Resilience near RAAF Base Pearce in Western Australia.

Here’s what you need to know about Andes virus, the risk of transmission, and how it’s different to the virus that caused COVID.

How do hantaviruses spread?

Hantaviruses are a group of viruses usually carried by mice, rats and other rodents. People are most commonly infected after inhaling tiny particles of contaminated rodent urine, droppings or saliva.

Most hantaviruses are not known to spread between people. Andes virus is the exception. After the initial spillover from infected rodents, it is the only hantavirus with well-documented person-to-person transmission.

But that doesn’t mean it spreads easily between people. Further human-to-human spread is uncommon, but it can occur in close-contact settings such as households, among caregivers, during intimate contact, or after prolonged exposure in crowded or poorly ventilated indoor areas.

That is very different from SARS-CoV-2, the virus that causes COVID. SARS-CoV-2 spreads very efficiently through the air. People could infect others before they even realised they were sick.

Early estimates suggested each person infected with SARS-CoV-2 passed the virus to roughly two or more others, on average, in populations who had never encountered it before.

Andes virus can cause onward human-to-human transmission, but requires a perfect storm of conditions: symptomatic people in crowded, poorly ventilated spaces with close contact over time. This was the case on the MV Hondius.

This difference in transmission potential is why SARS-CoV-2 caused a pandemic and Andes virus has only produced contained outbreaks.

What are the symptoms of Andes virus?

Early symptoms of Andes virus infection can look like many other illnesses, including fever, headache, muscle aches, nausea and fatigue.

In some people, infection can progress to hantavirus pulmonary syndrome, a life-threatening condition in which breathing becomes difficult.

How long after contact can you get symptoms?

The WHO recommends people exposed to Andes virus monitor for symptoms for 42 days after their last potential exposure.

This reflects the outer limit of the time between infection and symptom onset. It doesn’t mean people are infectious for 42 days.

Australian authorities have announced the returning passengers will initially spend three weeks in quarantine, with further monitoring arrangements to follow.

Melbourne’s Doherty Institute will undertake the testing using polymerase chain reaction (PCR), which detects the virus’s genetic material and blood-based antibody testing, known as serology.

A negative test early after exposure is useful, but not always definitive. If the virus is still incubating, there may not yet be enough viral genetic material or antibody response to detect.

How does the virus progress?

The long incubation period reflects how Andes virus progresses, compared to SARS-CoV-2.

COVID symptoms typically appear within days because the virus replicates rapidly in the respiratory system.

Andes virus progresses differently. Severe disease is linked to blood-vessel dysfunction and inflammatory responses. The breathing problems associated with the complication hantavirus pulmonary syndrome aren’t caused by the virus directly destroying lung tissue, but by the immune system’s delayed response. This causes fluid to leak into the lungs and makes breathing difficult.

How deadly is it?

Fatality rates vary significantly between hantavirus species.

European and Asian hantaviruses typically cause death in less than 1–15% of cases, while hantavirus pulmonary syndrome from American strains, including Andes virus, can reach up to 50%.

For context, in 2025, eight countries across the Americas reported 229 hantavirus cases and 59 deaths. These are severe infections, but they remain rare events.

A virus doesn’t become a pandemic simply because it’s deadly.

Read more: Hantavirus: here’s what you need to know about the infection that killed Gene Hackman’s wife, Betsy Arakawa

Can Andes virus be treated?

There is no specific antiviral drug for Andes virus. Health care for infected people focuses on close monitoring, supporting their breathing and managing complications to the heart and kidneys.

There is no licensed vaccine to prevent Andes virus.

However, there is also good news in how quickly the scientific response has come together after this outbreak started. Swiss laboratories collaborated quickly to sequence the complete genetic code of the virus from one patient and made it publicly available within days.

This gave researchers around the world a reference to compare other cases against. This can support faster confirmation of suspected cases, while helping public health teams identify which cases are linked to the outbreak and who needs monitoring or isolation.

Bottom line

The instinct to see another COVID in every viral outbreak is understandable but, in this case, misleading.

The Andes virus is dangerous to those infected, but it isn’t a good candidate for pandemic spread. It incubates slowly, typically spreads through close contact, and transmission appears most efficient when people are symptomatic.

It’s important to get the Andes virus under control but it’s not a pandemic threat like COVID.