There are 2.9 million, and of that number the department has indicated that 2.1 million are what they call dormant accounts on which there has been no activity; I'm not exactly sure for how long, but for an extended period of time.
The difficulty with those dormant accounts is that they are still valid numbers. They have not been cancelled, if you will, in the system. A flag will go up in the various departments that may be using that number to indicate that it was a dormant account. But not all the departments are treating those flags consistently, so there is still a risk.
The department is focusing, then, on the 800,000 others. There are processes they can do when people apply for various benefits. They will try to check the SIN number that way. They're trying to establish links as well with the vital statistics of the provinces.
I'm not sure that reissuing would solve the problem.