Maybe people don't understand what a "low dosage vaccine" means? If any vaccine at all can be created in time to help, why not have it be a "full dosage" vaccin

Maybe people don't understand what a "low dosage vaccine" means? If any vaccine at all can be created in time to help, why not have it be a "full dosage" vaccine and give it to everyone? But starting with young healthy people seems counterproductive, start with those at high risk of catching it (front line healthcare workers) and those at high risk if dying from it.