American Airlines reported its decision to operate service from Dallas Fort Worth to Shanghai Pudong via Seoul from 11-Nov-2020 was "due to testing requirements for crews" (Reuters/Fox Business, 02-Dec-2020). Additionally, United Airlines adjusted its San Francisco-Shanghai service to operate via Seoul, so as to include "a crew change", such as occurred earlier in 2020.
American Airlines, United Airlines adjust service to Shanghai to include Seoul
3 December, 2020