Vaccines rapidly lose efficacy when the virus they target has free real estate (vectors) in which to mutate. The laughably slow vaccine uptake in the US (while the rest of the world couldn't secure doses) is to blame there, not anything else.
Americans having to wear a cloth covering to keep their neighbors from catching something almost as contagious as measles is not a large ask, but here we are. It also protects against the flu and RSV since you're concerned about those—which is why the US didn't really have a flu season. Guess those couple hundred thousand deaths a year are preferable to masks when public outbreaks occur though.
What I don't understand is the rest of the world has figured this out? Go ride the subway in Japan and no one struggles with this, just westerners who think thatdoing the bare minimum to prevent illness, hospitalizations, and even death impede on their manifest destiny / freedom / constitutional rights / etc