1/ Update on what we know about the evolving hantavirus situation, strap in. A Swiss man linked to the ship has now tested positive after developing symptoms after disembarking. He received an exposure alert, sought care, and tested positive. This means there are 3 deaths and 5 suspected. 2/ It's also been confirmed that this is Andes virus, a hantavirus found in the Americas. The working hypothesis is that someone got this from a rat on an excursion, then unknowingly brought it on the ship. 3/ This type of hantavirus can spread person-to-person under specific conditions: prolonged, close contact with an infected person. Past Andes outbreaks have involved very close contact settings—caring for a sick person, sleeping in the same bed, or prolonged indoor exposure during symptoms. 4/ Cruise ships are uniquely high-risk environments for any infectious disease as they have shared air systems, tight quarters, and prolonged contact. That’s why investigators are treating all 150 passengers and crew members as potentially exposed. 5/ There may be another French case (but it’s uncertain at this point.) The rumors suggest that this may be from a plane. This isn't great news (obviously) but also not surprising. One woman left the ship a few days ago to be with her husband (that died), and then she also happened to get sick 6/ Data on the Andes virus suggest that it doesn't mutate quickly, so it's unlikely that, between the time on the cruise ship and the plane, the virus suddenly gained the ability to spread efficiently from person to person. 7/ In cases where transmission has been observed or believed to have occurred, even though it likely occurred via inhalation, there was still prolonged, close contact with someone who was symptomatic at the time (though mildly). This virus is behaving as we would expect, thus far. 8/ The big challenge here is the incubation period can be up to 6 weeks, so it takes time for biology to take hold and for the virus to start impacting someone. This means we'll likely see more cases in the weeks to come. We also have a really tough situation with these 150 people on board. 9/ Do you keep passengers on a ship that isn’t designed for isolation, or disembark into quarantine facilities? Neither is simple or low-risk. If they quarantine in a hotel, this would minimize mixing with other passengers, but also increases risk to others, specifically those transporting them. 10/ Additionally, it requires a country to allow the ship to dock, which seems challenging right now. 11/ Bottom line: This is not Covid-19. This is a serious and very unique outbreak that doesn’t have a playbook. Things are moving quickly but this virus is acting like we expect it to. The W.H.O says this is still a low risk situation. I'll be back with an update as this evolves.