Back in the realm of discerning causes from effects - or lack of effects - the current price of eggs in my part of California is insanely high and shelves are pretty sparse. This is due to large numbers of infected and possibly infected egg-laying chickens being killed to try to limit the spread of the bird flu. The "missing effects" is that despite the large number of infected chickens the number of chicken farmers infected is tiny or less. Bird flu isn't living up to the hype, as evidenced by the lack of infected poultry workers.
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WRT bubonic plague, the US has around 7 cases a year, and EuroLand about zero. The US and EuroLand are probably not be the relevant context. AstraZeneca is a British-Swedish company, and the actual developers of its vaccine were at Oxford University. Other than in clinical trials, the AstraZeneca vaccine was not used in the US. AstraZeneca never requested FDA authorization for its viral vector technology (= not Bogey-mRNA) Covid vaccine. The plague bacteria is endemic worldwide among animals, but human cases happen in Africa and South America. So if this vaccine is intended for current (after clinical trials and approvals) use, the context would probably be Third World countries. Or maybe it's an exercise in "just in case", though plague is treatable with antibiotics.