Step by step.
1>lockdown in order to diminish the circulation of the virus.
2> vaccination campaign while people are isolated in order to build their immune systems.
3> with a significant portion of the population already vaccinated, you could remove the lockdown restrictions and get back to a regular day to day activity. The virus might still spread, but since people were isolated, it's too contained and shouldn't cause much harm unless we get unlucky and it mutates to something resistant to the vaccines we have presently.
What ACTUALLY happened:
1> No lockdown. Only a few "case by case" restrictions AFTER a surge of contamination and hospitalizations.
2> Major antivax campaigns preventing people from both getting the vaccines (some countries delayed the purchase or couldn't get it sooner due to the high demand in the entire fucking world), or following the isolation protocols to prevent the circulation while people were being vaccinated.
3> An accelerated surge of different variants in different countries. Guess what? We were unlucky and some of these variants were even more contagious and/or lethal, and/or some of the vaccines that were being produced weren't effective against, almost bringing us back to square one.
4> A "running against the tide" action trying to "fix" the shit show already installed, with people, to this very day, STILL promoting antivax campaigns and making everything way harder that it should've been.