In some embodiments, a content management system can initiate a scan of a content item when the content management system detects that activity associated with the content item triggers a scan policy. In some embodiments, a content management system can initiate a scan of a user's account when the content management system detects that activity associated with the content item triggers a scan policy. A scan policy can specify, for example, a number of shares, downloads and/or previews of the content item allowable in a period of time. When the number of shares, downloads, and/or previews exceeds the specified number in the policy in the specified period of time, the content management system can initiate a scan (e.g., virus scan, malware scan, etc.) of the content item and/or the user's account.