Not so much our sovereignty, because the WHO basically thinks we can take care of ourselves, but the WHO definitely usurps a lot of other countries sovereignty. They are vaccinating children in Afghanistan and places like that, whether the local governments want it or not.They also seek to usurp our sovereignty.
If we want to rid the world of Polio, we need to rid the entire world of Polio, not just the parts of the world that have reasonable functioning governments.