The University released an updated International Travel & Reimbursement Guidance. In Summary:

• Travelers booking tickets through a Harvard preferred agency (Egencia, Travel Collaborative, BCD Travel, or Milne Travel) are automatically registered with International SOS and the agency receipt will serve as proof of registration. As long as this receipt is attached to the reimbursement, no further documentation is required.
• Travelers booking tickets through the airline directly or using other, non-preferred agencies, must include proof of registration in the form of either: 
  • The International SOS Itinerary & Travel Brief registration confirmation email, or
  • A screenshot of the registered trip in the International SOS My Trips system.
• If the traveler did not register or does not have their receipt, they will need to attach the Missing International Travel Registration Form to their reimbursement.

The Travel website has been updated to include this new guidance as well as the updated Missing International Travel Registration Form.