Genuine question

[LifesTooShortYOLO]

Just watching Jonathan Van Tams lecture on BBC 4 about vaccines and how they work.
It got me thinking how come Polio, SmallPox and measles etc never needed any boosters? They said it's lifelong immunity and protection once you've had it. But why not with the Covid vaccine?

Polio does - pretty sure I had a booster before I went travelling in my 20s. Think I had diphtheria booster, too. Also had Hep A and B and one of those came in 2 doses, with a booster within 10 years. Rabies was a series of 3 jabs. Japanese B encephalitis... I can't remember. Tetanus used to be every 10 years, or every 5 in high risk environments (lived on a farm,) but now they think if you've had 5 in total, that should be enough for life. I did have one smallpox jab, but I was one of the last. My sister (two years younger,) didn't ever have one.

I'd check on my immunisation record, but not at home just now.

Isn’t it because it’s more like the flu vaccine where they change the formulation every year to the strains they predict are going to be prevalent?

Covid chances as we’ve seen more than once in the past two years. That’s the issue. It looks like Omicrom gives immunity to Delta but not the other way round.

I can't remember exactly, but surely some childhood vaccine need boosters?

Measles has a booster.
Tetanus requires boosters.
Diphtheria requires boosters.
HIB requires boosters.
Probably others.