Could also be that Omicron hit just on the backside of a mass booster effort in UK while the US was caught months past the time we had a big booster push and immunity waned that it makes the efficacy appear a lot lower.
I'm laying big money on the ability of vaccines to prevent infection being a lot lower in the US. I'm also betting that timing boosters with waves becoming a big part of the battle against covid. It's really no different than what we do with flu vaccines because it is making little sense to push boosters at times that efficacy becomes reduced when needed.