Stir together wine, sugar, vanilla bean and seeds and 3 cups water in a pan large enough to hold pears standing up. Bring to boil over medium heat, stirring to dissolve sugar.
Reduce heat to low, add pears, cover with parchment and simmer until pears are tender, 20 to 25 minutes.
Remove pears to a bowl; set aside. Remove vanilla bean. Raise heat to high; boil poaching liquid until reduced to 1 1/2 cups, 35 minutes. Cover and chill pears and syrup.
Whisk yogurt and syrup together. Spoon sauce onto serving plates; place pear in center of each.