Moderna shares climbed sharply Monday after the company confirmed it had been conducting early research into potential vaccines targeting hantaviruses, as health authorities continue monitoring an outbreak linked to the MV Hondius cruise ship.

The pharmaceutical company’s stock rose nearly 6 percent shortly after markets opened, according to CNBC, following reports that Moderna had already begun preliminary work on hantavirus countermeasures before this month’s outbreak became public.

In a statement provided to The Independent, a Moderna spokesperson described the research as part of the company’s broader efforts to prepare for emerging infectious diseases.

“Moderna has conducted preclinical research on hantaviruses in collaboration with the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), reflecting the ongoing regional impact of these pathogens,” the spokesperson said.

The company also said it had partnered with the Vaccine Innovation Center at Korea University College of Medicine through its mRNA Access Program, which supports outside research on viruses considered potential outbreak threats.

The renewed attention around hantavirus followed reports of a respiratory illness outbreak aboard the MV Hondius, a cruise ship that docked near the Spanish island of Tenerife over the weekend. The World Health Organization said it received reports of the outbreak on May 2. Health officials later identified the illness as the Andes variant of hantavirus.

At least seven confirmed cases have been connected to the outbreak, and authorities said Monday that at least three people had died.

Despite the concern generated by the incident, the U.S. Centers for Disease Control and Prevention has said the overall risk to travelers and the wider American public remains “extremely low.”

Hantavirus infections can take between four and 42 days before symptoms appear, according to CDC guidance cited in the reports. Early signs often include fatigue, fever and muscle aches. Some patients may later experience headaches, dizziness, chills and stomach-related symptoms.

The disease can become severe once respiratory complications develop. The CDC says roughly 38 percent of patients who reach that stage could die from the illness.

Most passengers and crew from the MV Hondius have since returned home. The ship was expected to depart for the Netherlands on Monday evening, according to The New York Times.

U.S. health officials said the vessel had been carrying 18 American passengers. One American tested mildly positive for the Andes virus through PCR testing, while another developed mild symptoms.

The Department of Health and Human Services said an airlift operation would transfer affected passengers to specialized treatment centers in the United States, including the University of Nebraska Medical Center and Nebraska Medicine in Omaha.

“Upon arrival at each facility, each individual will undergo clinical assessment and receive appropriate care and support based on their condition,” the agency said in a statement issued Sunday evening.