I have to assume that a vaccine using legacy methods (let alone newer technology) would be easily achieved at this point, and that at least in humans, a possible outbreak could be blunted in under a year. So is it just not cost effective to do it for cattle?
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edit: leaving my original typed comment in place above. But I found this - https://texasfarmbureau.org/usda-approves-first-h5n1-vaccine...