The 2026 MV Hondius Andes virus outbreak: Implications for hantavirus research, vaccine development, and biosecurity

In May 2026, an outbreak of Andes virus (ANDV) infection aboard the expedition cruise ship MV Hondius resulted in 13 reported cases (12 confirmed and one probable) and three deaths. ANDV causes severe hantavirus cardiopulmonary syndrome (HCPS) and has a documented, although limited, capacity for person-to-person transmission after prolonged close contact. The transmission route in this cluster remains unresolved. Available evidence is compatible with common-source exposure before or during embarkation, limited close-contact transmission on board, or both. Definitive attribution will require linked epidemiological and genomic data. The outbreak exposed gaps in early clinical recognition, diagnostic access, surveillance coordination, risk communication, and the ready availability of medical countermeasures. This perspective has three aims: (i) to identify priority research questions concerning ANDV and related hantaviruses that have emerged from the maritime cluster; (ii) to evaluate the current state of vaccine and antibody development and establish priorities for epitope-informed design; and (iii) to propose practical biosafety and biosecurity measures for cruise operators, port health authorities, and reference laboratories. Countermeasure strategies should prioritize neutralization-sensitive conformational and quaternary epitopes on the N-terminal envelope glycoprotein (Gn) and C-terminal envelope glycoprotein (Gc). Nucleocapsid protein epitopes are exploited for surveillance and serological diagnosis. Rather than indicating uncontrolled community spread, the outbreak underscores the urgent case for integrated epidemiological, genomic, immunological, and operational preparedness for ANDV and related hantaviruses.