The science is very simple, get the shot and you reduce the likelihood of hospitalization or death. It's more effective for those with co-morbidities or those older in the age brackets.
I am not sure why this was politicized to death the way it has been. The mandates early on were to curb the hospitalizations / deaths that was occurring. Really the mandate should have been for people with co-morbidities or in the upper age bracket but you know what, people are stupid and everyone thinks they're healthy, so instead of being nuanced they applied it to everyone.