Important point towards low pandemic chance to me is that we saw it occur on a cruise ship. Those are tightly packed sure, but the chances that it originally started on the ship itself seems rather low. Assuming it is a new mutation, it either
Mutated in rodents that were already on the ship
Mutated in rodents on land that later slipped into the ship before sailing off.
Infected someone before they boarded.
Exceedingly unlikely but maybe it was planted there as a bioterrorism or something.
Both 2 and 3 pose the question of why the infection didn’t spread anywhere else. The infectee didn’t stay at a hotel the night before or spend time with anyone on land right before? The rodent didn’t happen to be near anyone on land and spread to them before it boarded? It’s not impossible, and maybe the incubation time was just long enough that it only started while on board the cruise, but that takes away from the likelyhood. Likewise it’s possible maybe some mouse or rat or whatever onboard just happened to be one that developed a new mutation but again, really unlikely.
That being said, we do have to face one issue. If Y is a possible (even if unlikely) cause of X, then observing X to be true means Y is way more possible than a non X world. We live in a world where hantavirus seems to have infected a significant amount on a cruise ship, thus while unlikely to be a major mutation that spreads human to human easily, it is something to be a bit concerned about.
We know it’s not a new mutation, that’s been confirmed. We also know where it started: two of the cruise ship passengers got infected while bird watching in a garbage dump in Ushuaia, Argentina. Argentina is one of the two countries that harbors the specific rodent species that are the main reservoires for Andes virus.
The clear sequence of events is that the tourists went to a rodent-infested location neither tourists nor locals frequent. This unusual decision exposed them to a much higher risk of infection from virus contained in aerosolized rat droppings in that setting. They were infected. Then they boarded the cruise ship, which sailed on. After an incubation period (which can last up to 6 weeks for hantavirus), the close quarters of the cruise ship enabled it to be transmitted to a limited number of other passengers, as we’ve seen in the limited number of reported cases of human-to-human transmission in the past, which took place at events like parties or among nuclear family members at home.
This incident has confirmed that hantavirus can undergo human-to-human transmission if the host is very sick and other people are in close quarters with them. It doesn’t appear to require physical contact in that circumstance. As I understand it, the human-to-human transmission cases have typically occurred when the patient is symptomatic, though we don’t know for sure about the risk of asymptomatic spread. Overall, however, it looks to me like it takes a rare, though not impossible, combination of events to result in human to human transmission that amount to it being too inefficient to pose even a high single digit risk of a pandemic.
I’d also add that, unlike COVID, the extreme danger of hantavirus means that if it were to show global outbreaks, the social reaction would be immediate and extreme. People would not be flying around and going out in public without extreme precautions if there was a 40% CFR virus with pandemic-level transmissibility. They’d be demanding lockdown. COVID-19 was in the perfect sweet spot for triggering a pandemic, being too low-risk on a case by case basis for the general public to instantly and uniformly lock down. Hantavirus is a different beast—to inefficient to be likely to transmit effectively, and too deadly to provoke the same cavalier behavior.
Important point towards low pandemic chance to me is that we saw it occur on a cruise ship. Those are tightly packed sure, but the chances that it originally started on the ship itself seems rather low. Assuming it is a new mutation, it either
Mutated in rodents that were already on the ship
Mutated in rodents on land that later slipped into the ship before sailing off.
Infected someone before they boarded.
Exceedingly unlikely but maybe it was planted there as a bioterrorism or something.
Both 2 and 3 pose the question of why the infection didn’t spread anywhere else. The infectee didn’t stay at a hotel the night before or spend time with anyone on land right before? The rodent didn’t happen to be near anyone on land and spread to them before it boarded? It’s not impossible, and maybe the incubation time was just long enough that it only started while on board the cruise, but that takes away from the likelyhood. Likewise it’s possible maybe some mouse or rat or whatever onboard just happened to be one that developed a new mutation but again, really unlikely.
That being said, we do have to face one issue. If Y is a possible (even if unlikely) cause of X, then observing X to be true means Y is way more possible than a non X world. We live in a world where hantavirus seems to have infected a significant amount on a cruise ship, thus while unlikely to be a major mutation that spreads human to human easily, it is something to be a bit concerned about.
We know it’s not a new mutation, that’s been confirmed. We also know where it started: two of the cruise ship passengers got infected while bird watching in a garbage dump in Ushuaia, Argentina. Argentina is one of the two countries that harbors the specific rodent species that are the main reservoires for Andes virus.
The clear sequence of events is that the tourists went to a rodent-infested location neither tourists nor locals frequent. This unusual decision exposed them to a much higher risk of infection from virus contained in aerosolized rat droppings in that setting. They were infected. Then they boarded the cruise ship, which sailed on. After an incubation period (which can last up to 6 weeks for hantavirus), the close quarters of the cruise ship enabled it to be transmitted to a limited number of other passengers, as we’ve seen in the limited number of reported cases of human-to-human transmission in the past, which took place at events like parties or among nuclear family members at home.
This incident has confirmed that hantavirus can undergo human-to-human transmission if the host is very sick and other people are in close quarters with them. It doesn’t appear to require physical contact in that circumstance. As I understand it, the human-to-human transmission cases have typically occurred when the patient is symptomatic, though we don’t know for sure about the risk of asymptomatic spread. Overall, however, it looks to me like it takes a rare, though not impossible, combination of events to result in human to human transmission that amount to it being too inefficient to pose even a high single digit risk of a pandemic.
I’d also add that, unlike COVID, the extreme danger of hantavirus means that if it were to show global outbreaks, the social reaction would be immediate and extreme. People would not be flying around and going out in public without extreme precautions if there was a 40% CFR virus with pandemic-level transmissibility. They’d be demanding lockdown. COVID-19 was in the perfect sweet spot for triggering a pandemic, being too low-risk on a case by case basis for the general public to instantly and uniformly lock down. Hantavirus is a different beast—to inefficient to be likely to transmit effectively, and too deadly to provoke the same cavalier behavior.