CORRESPONDENCE 12 May 2026 By César López-Camacho University of Oxford, Oxford, UK. You have full access to this article via your institution. The hantavirus cluster on the cruise ship MV Hondius is unusual and severe. Your News Explainer rightly focused on uncertainties, including the source of exposure, transmission route and viral identity (see Nature https://doi.org/q5qs; 2026). This outbreak, thought to be caused by the Andes virus, a New World hantavirus, exposes a broader preparedness gap. New World hantaviruses are too rare in absolute numbers to command sustained attention, yet too lethal and too epidemiologically distinctive to be treated as routine diseases that spread from animals to humans (zoonoses). More than just increased funding is needed. Vaccines against hantaviruses are in development (see Nature https://doi.org/q5ww; 2026 ). Platforms using messenger RNA and adenovirus vectors now enable rapid antigen design and generation of candidate vaccines.…