The fix is deployed from the service and no changes are needed from the client or the user to get the fix. The fix will prevent any new occurrences of the issue.
If you have users that have calendar conflicts with the diamond indicator on the meeting then they still need to do Clear Offline Items, New OST, or new Outlook Profile to clean those up.

If users have duplicated meetings because they clicked Keep All on the Conflict Message dialog that can be mitigated using Calcheck. When you use Calcheck you have to edit a config file to tell it what items to move off the calendar. Its important to make sure users edit the calcheck.cfg file. I am updating the Known Issue with a sample calcheck.cfg file you can use or reference instead.
The mitigations are listed in the Known Issue and has pending updates that will go live shortly, Outlook shows conflict errors when updating or cancelling meetings - Microsoft Support.