[Mediterraneo10]

No, the vaccinations required for travel were virtually never expected to be taken on an annual basis but rather were good for years. For example, not only was the UN yellow-fever vaccination certificate good for 10 years, but recently the WHO announced that the yellow-fever vaccine now appears to confer life-long immunity, so border officials should accept the certificate regardless of the date on it.

[msbarnett]

That's just the luck of the draw, though. Yellow Fever happens to be amenable to life-long immunity. COVID (may) not be.

Had the situation been reversed, you'd have had to get Yellow Fever vaccinations a lot more often if you were travelling into those regions, and the COVID situation would be one-and-done. It just happens that this is the way it worked out, instead. There's nothing dystopian about this.