posted by HereticWell, that's how it's been for flu shots, at least for those who get those annually, so I wouldn't know why a person would think a variant would be one-and-done.
Pretty much only for flu shots. Most other vaccines last years, if not a lifetime. And that's normally the case with coronaviruses. Mutations is a different story.
But flu shots only provide protection for 6 months, and variant specific. Again, coronavirus vaccines aren't flu shots. Flu shots are kind of the exception here.