Not proof at all. People who might ordinarily die sometimes live. Some live, some die. Proves nothing.
All that were infirm during the time of Jesus were not healed. But many were, and miraculously so. So it is in our current age. While we do not know why God chooses some to be healed and not others I will have mercy on whomever I will have mercy, He says, and I will have compassion on whomever I will have compassion we do know that some are indeed miraculously healed, according to Scripture, for the Glory of God.