A centralized database for single payer universal health care would be a good idea to use as backup, but the entire idea is too big for daily use, even with the development of new Big Data management tools. Smaller directories still need to be used on the town and city scale, too.
A centralized database allows for too much infringement on privacy and personal liberty. The government should not know when your last cold was, or your family history of cancer. The government's role is to protect personal property and physical safety from others, not to keep track of physical health histories. A centralized database is too much infringement on privacy from government.