I'd say that there are two levels of screening for all personnel who require clearances.
There is, of course, the security screening process, which we've already discussed here, including reliability status, including criminal and Canadian Security Intelligence Service checks.
There is also a separate Human Pathogens and Toxins Act clearance that's required to work with any sensitive listed materials. It also requires additional training in the use of those pathogens, as well as a separate security clearance that must be granted by the regulator.