A virus has infected client machines on your network and is spreading to other machines.
NOTE: This will trigger the SEPM Console to issue the command out to all the clients. This command will not show up as complete until all clients that the command was issued to have reported back completion of the scan. If any of the clients in the group fail to report back, the command will show up as incomplete even if all the clients have received the command and completed the scan.
You can see the status in Monitors option over Command Status tab.