So, I understand this, and I absolutely support evidence-based medicine. I guess I'm at a loss as to why decades of giving this vaccine to folks 50+ is not sufficient to assess risk for people under that age, or never inspired more study into side effects. I also think that people who are 50+ are living long enough these days that we could probably make a good assessment as to how long the vaccine lasts (if we're not assessing that, I'd be kind of surprised and concerned as to why not).

Prioritizing drugs in the event of shortages is totally understandable, though pretty easily fixable if you give the manufacturers time to plan for general availability (hopefully they would see it as an opportunity to make money by broadening market share, not an opportunity to make money by restricting supply).