On August 12, 2021, the U.S Department of State updated their website posting on National Interest Exemptions (NIE) with some additional frequently asked questions (FAQ).
Of specific interest is an FAQ that states that a person would not need to get an NIE issued by the US Embassy/Consulate for each travel restricted country visited on a trip, but that one NIE would cover travel to multiple regions:
“If I receive an NIE to travel from one region under a COVID-19-related presidential proclamation, can I use the same NIE to travel within 12 months from a separate region that is also under a COVID-19-related presidential proclamation restricting travel?
Yes, all valid NIEs approved by the Department of State apply to all COVID-19-based Presidential Proclamations.”
ISchO recommends that international scholars who have been in a country subject to U.S. travel restrictions [new Link TBA https://web.mit.edu/scholars/news/index.html#immigrationupdates35], and who require an NIE, check with their airlines before arriving at the airport, to be sure they they will have all the appropriate documentation needed to board the airplane bound for the U.S