characteristic about health boost

I think that when you give someone "health_boost" effect, it shouldn't change his health into 20, instead, it should keep his original health, and this way this effect won't lock someone's health when using repeating command. But if that person has more than his max health? Well, I think that when the time of this effect is up, the extra health will become "single absorption", it can absorb any damage less than extra health once, and then this "absorption" will disappear.