Epistemic status: a few people without any particular expertise in epidemiology spent an afternoon in a coffee shop discussing and reading about H5N1, with a focus on how an individual should orient towards this (as opposed to say, the government). This is a write-up of what I took away from that exercise, written from my perspective. Some ideas were generated in collaboration with Claude but generally spot checked. This post was also sanity-checked by a friend who works in epidemiology. I feel ok about the ideas presented but would not be surprised if someone with more expertise has a significantly different conclusion. Any mistakes are mine. I went into this exercise with a prior of “I’ve been hearing about bird flu for years, and it’s always been nothing, it’s probably nothing again this time.” The main upshot is that I walked away from the exercise thinking “I don’t know if this is going to be something or not.” As far as updates go, that seems directionally bad. My current orientation towards this is something like “watch and wait, and spend appropriately more effort on this if / when certain milestones happen (and also make some trades).” What’s different this year? One main thing that seems to generate a heightened level of ongoing risk is sustained infections in dairy cow populations. This is already bad because it’s mammal-to-mammal transmission in a population that hasn’t historically had problems with bird flu, and it would be worse if it becomes endemic in farmed cows. As long as it is sustaining infections in farmed cows, H5N1 has a convenient breeding ground for mutations that is: * In a high density population * Year round (bird flu is seasonal among birds) * In regular contact with humans The last point gets a bonus with the human flu season coming up. If a dairy worker gets sick with both bird flu and human flu simultaneously, the two strains might share their genetic information and mutate into a pandemic-worthy strain. Another thing bei