Moderna's stock experienced a notable uptick in premarket activity after U.S. health authorities disclosed that a passenger on a repatriation flight had tested positive for the Andes strain of hantavirus. By 05:38 ET, the company's shares were up roughly 7.7% in premarket trade.
The Department of Health and Human Services (HHS) said the person who tested positive exhibited only mild symptoms, while a second individual on the same flight was reported to be showing mild symptoms. Both were among 17 American citizens who had been evacuated from the MV Hondius cruise ship and were being transported to the United States.
According to HHS, the two passengers were occupying the aircraft's biocontainment units as a precautionary measure - a step described as being taken "out of an abundance of caution." The flight carried all 17 evacuees to the United States, and officials have characterized the clinical presentations as mild.
Moderna has publicly acknowledged it is investigating a hantavirus treatment. The company described those efforts as "early-stage and ongoing" and said the work falls within a broader focus on emerging infectious diseases. In 2023, Moderna entered a research agreement with Korea University to pursue a hantavirus vaccine under its mRNA Access Program.
No licensed vaccines or targeted antiviral therapies for hantavirus exist at present. Medical management of hantavirus infections remains primarily supportive, aimed at stabilizing patients while the body clears the infection and recovery takes place.
"Research to help us develop vaccines and develop treatments is urgently needed," said Carlos del Rio, former president of the Infectious Diseases Society of America.
The strain identified among the cruise ship passengers, the Andes virus, is known to be endemic in South America, the region where the vessel originated. The Andes variant differs from most hantavirus strains in one important respect: while the majority of hantavirus infections are associated with exposure to the urine, feces, or saliva of infected rodents, the Andes strain is among the small number of hantavirus types known to be capable of human-to-human transmission, although such transmission is considered rare.
This market reaction highlights investor attention to biopharma firms conducting research on emerging pathogens. Moderna's early-stage hantavirus program and its 2023 collaboration with an academic partner were followed closely by market participants after the HHS disclosure about evacuees from the MV Hondius.