A close friend of mine (40, male, in great shape) was boosted 30 days ago. Came down with a very nasty case of Covid a week and a half ago that knocked him down big time for about a week. So as to your question of "how effective would that even be at this moment", my observational experience would lead me to answer "maybe good, maybe great, or maybe not at all effective". There seems to be little rhyme or reason to it.