I'm not sure what you mean, tetanus shots actually last 30+ years.

You need a booster every 10 years to maintain immunity.

No, there's quite a bit of evidence that they last much longer than that.

You may not have complete immunity beyond 10 years though, so the recommendation is that you get a booster every 10 years.

But I don't see your point? Are you arguing that the COVID vaccine grants immunity for much longer than advertised? That seems unlikely given the mutation rate of coronaviruses.