Vaccines could potentially reduce short-term risk while increasing risk in future
This (preprint) study suggests that repeat vaccination with the same sequence may have serious downsides.
https://www.medrxiv.org/content/10.1101/2021.08.12.21261952v2
If you repeatedly vaccinate people with the "original Wuhan sequence" (as we're currently doing with the Pfizer or Moderna boosters) this could lead to people being protected against an old variant that is no longer in circulation, but _more_ susceptible to currently circulating variants. It could also cause a range of other autoimmune disorders.
There are a few other studies on this. Eugyppius' substack is full of interesting content - this one discusses a couple of studies that explore the impact of "Original Antigenic Sin":
Essentially, if your body is exposed to a virus, it remembers that virus. If it's then exposed to a similar but different virus, it might not respond as well as if it'd never been infected with the first virus, because it remembers this previous infection. The same can apply for vaccines, and it seems likely that repeat vaccination with the same sequence could compound this effect.
I would advocate pausing "booster" programmes until the long term impacts of this are better understood and factored in to the risk-benefit calculations.