I feel as though early jungle invades are too safe for the invader. To be clear I'm talking about solo invades typically where the enemy will try to invade you while your fighting your buff. As the one being invaded its hard to fight the invader because you are tanking a buff which early is basically another champion as well as you missing more health and resources than the invader due to trying to fight the buff. You can ask your teammates for help but by the time they respond the damage can already be done (you die, buff stolen, sums burned) and it may not even be worth for your team to respond losing out on early cs an xp for a potential kill.
As the one being invaded your options are to fight the invader while the buff is attacking you. Try to drop aggro of the buff and hope it switches to them but then they can just do it since its lower, you're hurt, and since they are the one that planned the invade may have saved smite for the invade. Or you can back off entirely and forfeit it. Even if you ward early and see it coming you are still at the mercy of your team coming to help. Even if the invader gets nothing out of it (no buff steal, kill, blow sums) they aren't losing much from it either unless they die or have to blow their own sums which again probably won't happen unless you receive help.