Interim Clearances Are NOT Less Than Full Clearance
A mistake that often appears in media reports about clearances is saying that a person has only an interim clearance and so does not have "full" clearance. This language is incorrect and misleading.
An Interim clearance is not "interim" because it provides less than full access. It is "interim" because it is a temporary clearance pending the final adjudication of the person's background investigation. An Interim clearance provides full access to classified information, however, (at whatever level the person is being submitted for access, for example, Secret).
An Interim clearance is granted because a preliminary review of the person's application shows nothing that is likely to be a basis for denial of the clearance. As most people who apply get their clearances, it makes sense to have this preliminary determination so that people can begin to work while their investigation is in process. Overall, a tiny fraction of Interim clearances are withdrawn because the person is proposed for denial of clearance. On balance, the efficiency gained by issuing Interim clearances is great and the risk to security is low.
Because the Interim clearance is a decision by an adjudication to temporarily provide full access to classified information at the level requested, there is NO reason for anyone else to be uncomfortable or unwilling to share information with the person holding Interim clearance. Doing this effectively is second guessing the adjudicator without any basis for doing so. This would be different if the person has a first-hand reason to suspect the person with Interim clearance is untrustworthy. In that situation, the person should be promptly reporting their information to security officials. But there is no basis to consider someone with Interim clearance to be suspect simply because their final adjudication has not come through yet.