The Passover, being the first of the Seven Feasts required be observed at the appointed time, is no longer a yearly feast--it's a person. Jesus puts an end to the Passover rituals for believers. He is the sacrifice for the sins of the world--slain for us. The institution of the Lord's Supper at Passover signals the end of Old Testament Passover with the offering of the true Passover Lamb. Jesus was and is that offering.