MV Hondius Outbreak: A Wake-Up Call for Hantavirus Research

The deadly hantavirus outbreak aboard the cruise ship MV Hondius has thrust a rare and often overlooked pathogen into the global spotlight. For most scientists and public health officials, hantaviruses typically attract little attention because they rarely infect humans and seldom spread between people. However, the situation in the middle of the Atlantic Ocean revealed a dangerous gap in medical preparedness.

Currently, there are no targeted treatments or widely available vaccines for hantaviruses. This lack of medical countermeasures left doctors and public health experts with very few options as passengers began falling ill. “It’s kind of a wake-up call,” said Dr. Vaithi Arumugaswami, an infectious disease researcher at the University of California, Los Angeles. “Our tool kit is almost empty.”

The Rare Threat of the Andes Virus

Hantaviruses are generally categorized into two groups: Old World viruses, found primarily in Europe and Asia, and New World viruses, found in the Americas. The outbreak on the MV Hondius is linked to the Andes virus, a New World strain endemic to South America.

The Andes virus is uniquely dangerous because it is the only hantavirus known to spread from person to person. Most other strains are carried by rodents and transmitted to humans through contact with rodent urine, droppings, or saliva. Because hantaviruses are not typically airborne or highly contagious, they have not been a high priority for pandemic prevention groups, according to Jay Hooper, a virologist at the United States Army Medical Research Institute of Infectious Diseases.

The Race for a Vaccine

While some vaccines exist for Old World viruses in Asia, experts note that their efficacy is modest. For New World viruses, including the Andes virus and the Sin Nombre virus found in the western United States, no licensed vaccines exist.

Despite the lack of approved options, several promising candidates are in development:

• DNA Vaccines: Jay Hooper and his team developed a DNA vaccine for the Andes virus. In a small phase 1 trial, more than 80 percent of participants produced neutralizing antibodies under certain dosing regimens. While the vaccine may require at least three doses, Hooper notes the science is complete and simply awaits government demand or market forces to move forward.
• Nasal Vaccines: Bryce Warner, a researcher at the University of Saskatchewan, is exploring nasal vaccines to trigger a more robust immune response in the airways. This research is currently in the early stages and is being conducted in hamsters.

Moving these vaccines into human trials is difficult because hantavirus cases are so rare. “It’s very difficult to conduct a clinical trial when you only have a limited number of cases annually,” Warner explained. “You don’t have the numbers of people to really show a robust effect.”

Treatment Options and the “Empty Toolkit”

Standard clinical response for hantavirus currently relies on supportive care, such as supplemental oxygen or heart-lung bypass machines. Some doctors use an existing antiviral drug called ribavirin, but scientists say there is no strong evidence that it works against New World viruses.

Researchers are hunting for more effective alternatives:

• Broad-Spectrum Antivirals: Dr. Arumugaswami and his colleagues at UCLA found that favipiravir, a drug approved for influenza in Japan, inhibited the Andes virus in human cells. They have also identified other compounds with broad antiviral activity using human organoids.
• Therapeutic Antibodies: Kartik Chandran, a virologist at the Albert Einstein College of Medicine, isolated natural antibodies from hantavirus survivors. In hamster tests, one specific antibody worked against both Old and New World hantaviruses, even when administered late in the infection.

The Funding Gap: Why Progress Stalls

The primary obstacle to saving lives from hantavirus is not a lack of science, but a lack of funding. Because the virus is rare, there is little commercial interest in developing a product.

Dr. James Crowe, director of the Vanderbilt Center for Antibody Therapeutics, states that his team has a lead drug but lacks the necessary financial support to proceed. “We need is someone to pay the money, which would be something like $40 million, to go the next step,” Crowe said. He noted that they currently have no support from companies, foundations, or the government.

Dr. Ronald Nahass, president of the Infectious Diseases Society of America, believes that while some interventions are “sitting there on the bench” and could be developed quickly if prioritized, nothing is currently ready for clinical use.

Key Takeaways

• Pathogen: The MV Hondius outbreak involved the Andes virus, the only hantavirus capable of human-to-human transmission.
• Current Care: Treatment is limited to supportive care; no licensed vaccines or targeted antivirals exist for New World hantaviruses.
• Promising Leads: A DNA vaccine has shown over 80% antibody production in early trials, and antibody treatments have shown success in animal models.
• Main Barrier: A lack of commercial and government funding (estimated at $40 million for some lead drugs) has stalled the transition from lab to clinic.

Experts hope that the MV Hondius outbreak creates a lasting shift in how the medical community prioritizes hantaviruses. While the virus may eventually fade from the headlines, the goal is to secure the resources necessary to ensure the “toolkit” is no longer empty when the next outbreak occurs.