Is There a Pandemic Class Threat?

We do not try to map out every possible way that one could make a nuclear weapon and share it with international atomic energy agency inspectors so they know what to look for. It's much harder for the kinds of folks who want to gain access to nuclear weapons to do that kind of research than it is for well resourched governments in a position to do this. So it's actually contrary to our interests to map out the threat space surrounding the details of how to make nuclear weapons. Even if telling them would help inspectors do their job by preventing misuse, we still have decided we don't do that because we cannot defend against these things.