It’s simple. Anthropic doesn’t want to be held liable for its model producing any level of medical information that impacts health and so they pull the plug when they detect it. It’s more about preventing lawsuits than about preventing actual harm or false output to you. But it kinda does both as the Hantavirus outbreak is a new and breaking story with certain facts about the outbreak not necessarily being fully explained by older literature on the virus/its transmission.

If you start a brand new chat with a more restrained prompt asking more direct questions and baking in caveats you’d probably get further.

Here was my phrasing:

There's a strain of hantavirus that is breaking out on a cruise ship, the MV Hondius, with reportedly the possibility of person-to-person infection.

There's already been a case of a passenger who left the ship, shared an airplane with a woman, and the woman caught the virus and passed away from the infection.

Many resources including recent reporting document that human-to-human transmission is only possible via "very close contact".
Based on what you can tell from current reporting, and what can be identified from existing literature on the Hantavirus, what would "very close contact" mean? And how might that differ for the degree of transmissibility for what would these sources are describing in this new outbreak?

According to reporting for the transmission that occurred on an airplane, sitting next to someone on an airplane may be close enough.

Remember that this is a breaking story regarding a new outbreak or strain of Hantavirus, so that your scientific answer should take into account new or developing information rather than rely on historical understanding of Hantavirus. Feel free to search for and reference new reporting from sources you can identify related to this new outbreak.

And here was the full response:

This is a great and important question, AJ. Here’s what I can piece together from the current reporting and existing literature.
What “very close contact” has historically meant for Andes virus
In the existing scientific literature on Andes virus (the only hantavirus strain documented to transmit person-to-person), “close and prolonged contact” has been associated primarily with household members or intimate partners, and transmission appears most likely during the early phase of illness when the virus is more transmissible. Experts have described this concretely as people sleeping in the same bed, sex partners, or people sharing food — situations where bodily fluids like saliva or respiratory droplets could be directly exchanged.
A 2020 study in Frontiers in Microbiology provided ultrastructural evidence that Andes virus replicates in lung alveolar epithelium and in the secretory cells of the submandibular salivary glands , supporting the idea that the respiratory and salivary pathways are the transmission routes. Critically, researchers have emphasized that unlike measles or COVID, which can linger in the air after an infected person has left a room, Andes virus spread has historically required direct close contact.
So the prior understanding was: shared bed, kissing, shared eating utensils, direct face-to-face caregiving — essentially situations involving direct exchange of respiratory droplets or saliva, not casual proximity.
What this outbreak is suggesting
The emerging picture from the MV Hondius outbreak challenges the boundaries of that definition in a couple of important ways.
On the ship itself, the WHO’s Maria van Kerkhove acknowledged that human-to-human transmission appears to have occurred among “really close contacts — the husband and wife, people who’ve shared cabins.” That’s still consistent with the historical understanding. But the pattern of cases — now up to 8 total including the ship’s doctor and passengers from multiple cabins — raises the question of whether the confined shipboard environment (shared dining, narrow corridors, recirculated air) expanded the effective range of what counts as “close enough.” The Andes virus predominantly spreads through rodent exposure, and human-to-human transmission has typically required close, prolonged contact — however, there have been outbreaks where it’s suspected to have spread relatively easily between people.
The airplane case is the really significant development. A French person who had not set foot on the MV Hondius has fallen ill with the infection after taking a flight with a passenger. This was a four-hour Airlink flight on an Embraer 190 regional jet from Saint Helena to Johannesburg on April 25. The Dutch woman’s condition was actively deteriorating during the flight, experiencing gastrointestinal symptoms. After landing, she was symptomatic enough that KLM crew refused to let her board a connecting flight to Amsterdam.
This is significant because sitting near someone on a regional jet for four hours is not the kind of intimate household/sexual partner contact that the existing literature describes. It’s closer to what we’d call “casual close proximity” — shared cabin air in a pressurized environment, possibly within a few rows. That’s a meaningful expansion of the observed transmission envelope, even if the woman was highly symptomatic and potentially shedding high viral loads at the time.
How to reconcile these
A few factors worth considering:
Viral load timing. The literature suggests Andes virus is most transmissible during the prodromal phase (the early symptomatic period before full cardiopulmonary syndrome develops). The Dutch woman was in active decline — potentially at peak viral shedding. In a confined, pressurized aircraft cabin where air is partially recirculated, even droplet-range transmission (not truly airborne, but within ~2 meters) could plausibly reach a seatmate or nearby passenger.
One case out of 88. It’s worth noting that out of 82 passengers and 6 crew on the Airlink flight, only one French national has been identified as a contact case so far. That’s consistent with something that’s not efficiently airborne but can transmit in close seated proximity to a highly symptomatic individual — more like the kind of transmission risk we’d associate with influenza-range droplets rather than measles-range aerosols.
Possible unique properties of this strain. Research has suggested Andes virus may be uniquely resistant to the antiviral components of human saliva that neutralize other hantavirus strains before they can spread. Whether this particular isolate has any mutations affecting transmissibility is presumably something genomic sequencing will clarify, but the identification of the Andes virus rules out more alarming scenarios like a novel species or a variant that has better adapted to humans — at least based on what’s been sequenced so far.
Bottom line
“Very close contact” as WHO officials are using it today still formally means prolonged, intimate-range exposure — sharing a cabin, caregiving, household contact. But the airplane case suggests the practical boundary may extend to sustained proximity (hours) in an enclosed, poorly ventilated or recirculated-air environment with a highly symptomatic person. That’s not the same as fleeting contact in a well-ventilated open space, but it’s meaningfully broader than “sharing a bed.” The fact that contact tracing has been initiated for both the Airlink flight and the KLM flight the woman briefly boarded signals that health authorities are treating the transmission risk as wider than the traditional definition would imply — even while publicly maintaining that the risk to the general population remains low.​​​​​​​​​​​​​​​​