The hantavirus outbreak that has killed three people and put 12 countries on alert is less contagious than COVID and likely won’t turn into a major pandemic, a leading hantavirus researcher told The Post. Officials are scrambling to track and potentially quarantine people who may have been exposed to a rare, human-to-human strain of hantavirus aboard an Atlantic cruise ship, including at least six Americans . Hantavirus — which normally spreads via mouse droppings and killed Gene Hackman’s wife last year — has a mortality rate as high as 40%, but it’s harder to spread than COVID-19, said epidemiologist Ali Khan. The MV Hondius, site of a hantavirus outbreak that has killed three passengers and infected several others. AFP via Getty Images Medics bring a patient evacuated from the MV Hondis into an ambulance. AP Dr.…