From what I've seen, there is no risk in being vaccinated when you already have prior infection, and there are benefits to doing so. So I don't see why prior infection would constitute a good medical reason to avoid vaccination.

(Aside: it is worth noting that vaccination also induces "natural immunity", as it introduces viral units [via various mechanisms depending on specific vaccine type] that cause the immune system to work more or less the same way as it would if presented with a regular viral infection. So using the term "natural immunity" when what you really mean is "prior infection" smacks quite heavily of chemophobia.)

No it’s not because the risk of getting serious illness is/was much higher compared to any vaccine. The risk of death is certainly higher. Again getting vaccinated is a no brainer on the face of it.