What do return passengers need to prepare for China Eastern Airlines flight?

I saw in the news before that not only the flight of China Eastern Airlines, but also Chinese and foreign personnel who take the flight to China should complete the nucleic acid test in the testing institution designated or recognized by the China Embassy and Consulate within 3 days before boarding. Passengers are required to complete the nucleic acid test according to the notification requirements of the local embassies and consulates in China, upload the negative certificate of nucleic acid test through the international version of the epidemic prevention health code applet, and obtain the nucleic acid code after being examined and approved by embassies and consulates in China, so as to board the plane with this code.