But @boys this isn't presumably what FWNBC wants, as they're wanting someone else to have the vaccine to protect them. So it's about preventing infection, data isn't as great on that, and it's contradictory (Pfizer releasing studies showing good protection after 6 months on the same day as saying protection wanes and you need a booster) and you have limited information on the chance of infecting someone else with a breakthrough infection, although it's probably lower (certainly lower than anyone with a longer infection due to being sicker)
The Zoe study last month ( covid.joinzoe.com/post/covid-vaccine-protection-fading ) reckoned on 75% or 67% at 5 months depending on vaccine.
If that continues to get worse, then I am not sure of the reliance you can really get, or the worthwhileness of someone vaccinating themselves to protect another. Right now, past infection is considerably better than the above, if I really wanted to be sure of protecting someone I'd get infected whilst not seeing them, not rely on the not great vaccines, but vaccine alone will reduce the chance in the short term at least.