I don’t really think that’s it. Definitely a difference in the way certain areas/health systems are pushing Covid vaccinations/boosters. And it’s definitely along political lines.
You're wrong.
From 2007-2019, every single year, I would be headed to the company cafeteria and see that there was a line of people getting flu shots. Oh yeah, the free flu shot day is here. Was just a company "perk" (or as MN would say, a company control mechanism to mess up our precious bodily fluids). I'd get my shot and never think about it again - but the availability and PR campaigns were always there. When you go to Xmas, you didn't tell a story of how you were at CVS to get your flu shot, and ran into Timmy, you just told a story about running into Timmy, because getting the flu wasn't really anything we spend societal mental energy on. And if for some reason I mentioned getting a flu shot, it probably wouldn't cause any additional conversation, it would just drift away. Meanwhile when my Nephew got COVID at Xmas, we probably wasted hours of conversational time on "I was gonna get a booster but" "Oh I got the booster" "I figured I got it this summer so I wasn't gonna go out of my way".
COVID is a proper noun, flu is a noun. We *notice* the outreach more.
This said, I would not be shocked if higher levels of funding are being put into PSAs for COVID than Flu shots got. And when I heard an ad on the radio the other day about Social Distancing I admittedly laughed. I do give the side eye to anyone coughing and hacking in public, but the only real social distancing I note these days is people with those damn little dogs that always bark at my normal sized dog. I walk straight at them and laugh as they cross the street or pick up their annoying fleabag.