Why This Hantavirus Outbreak Is Not Another COVID

The last passengers from the virus-stricken cruise ship MV Hondius have now been flown to the Netherlands, while new infections continue to be identified. The images of quarantined travellers and worried communities inevitably evoke memories of COVID-19. But public health experts say the comparison ends there.

At the centre of the response is the rare Hantavirus Pulmonary Syndrome, caused in this case by the Andes strain of hantavirus. It is a dangerous virus with a high fatality rate, but it spreads very differently from the coronavirus that shut down the world in 2020.

“I need you to hear me clearly: this is not another COVID. The current public health risk from hantavirus remains low. My colleagues and I have said this unequivocally, and I will say it again to you now,” said Tedros Adhanom Ghebreyesus, head of the World Health Organization.

Hantaviruses are primarily carried by rodents, which shed the virus in urine, saliva and droppings. Humans usually become infected by inhaling contaminated particles. Unlike COVID-19, which spreads efficiently through casual contact and airborne transmission, hantavirus is generally much harder to catch.

The Andes strain is unusual because it is the only hantavirus clearly shown to spread from person to person. Even then, transmission appears to require close and prolonged contact, such as sharing a household or caring for an infected person.

“Occasional human-to-human transmission events may occur but require specific circumstances and long exposure times,” said Tomas Strandin. “However, infections via rodents are becoming more widespread due to climate change, but these are local infection events.”

That distinction is crucial. COVID-19 was highly contagious because the virus replicates readily in the upper respiratory tract, allowing infected people to spread it simply by breathing, talking or coughing. Hantaviruses typically infect deep lung tissue and blood vessels, where they can cause severe illness but are much less likely to be expelled in large quantities.

The current outbreak began after the Hondius departed Argentina on April 1. Health authorities believe some passengers were exposed before boarding, in a region where the Andes strain is endemic.

Three people — a Dutch couple and a German tourist — have died. The WHO has now confirmed 11 infections linked to the voyage, including cases identified in Spain, the United States and other countries as passengers are repatriated and monitored.

A total of 94 people have been evacuated to about 20 countries, where they are undergoing quarantine and medical observation. The virus can incubate for up to eight weeks, which explains the unusually long monitoring period.

Officials from the European Centre for Disease Prevention and Control say all passengers are treated as high-risk until the incubation window closes.

“Passengers and crew continue to disembark and to be medically evacuated to their countries of origin. At disembarkation, they are all considered high-risk and repatriated, whether symptomatic or not, through noncommercial flights,” said Gianfranco Spiteri.

The precautions are strict because hantavirus can be deadly. According to the US Centers for Disease Control and Prevention, Hantavirus Pulmonary Syndrome kills roughly 40 percent of those infected. But severity is not the same as transmissibility.

COVID-19 became a pandemic because it spread quickly and easily between people, often before symptoms appeared. Hantavirus moves far more slowly and requires much closer exposure, giving health authorities time to isolate contacts and prevent wider transmission.

“People shouldn’t panic since human-to-human transmission is so rare that a pandemic is impossible,” Strandin said.

The ship itself is now en route to Rotterdam, where it will be disinfected. What remains is a painstaking effort to monitor passengers, trace the original source of infection and reassure a public still shaped by the experience of COVID.