Arrange travel so that you do not transit through a banned country.
Pretty much anyone can travel to the United States provided that the traveler has not been within one of the banned countries within 14 days before boarding their flight: https://www.cdc.gov/coronavirus/2019-ncov/travelers/from-other-countries.html.
Update July 6, 2021: Effective immediately, all National Interest Exceptions (NIE) are valid for 12 months and multiple entries. If you have received a pervious NIE in the past 12 months, it will remain valid until one year after its original approval date.
Within the email itself rather than attached as a PDF template, the following info is necessary (in addition to attaching supporting documents such as passport, ESTA/Visa, all Embassy correspondence, Employer Letter/ Invite Letter, confirmed flight itinerary, booking, & a scanned G-28 copy)
All requests must include: