You just quickly googled that, of course. Before that you had no idea what HIPAA was
The government doesnt have access to HIPAA unless it necessary for law enforcement to do so, but that can only be done
after a crime has been committed.
Its simply not allowed that the government get access to the HIPAA database and get a hold of medical records for 47% of the country who might have mental health issues.
So again, if you dont know the names of all Americans who might have mental illness, how can you prevent them from buying firearms??