Chinese customs screened 600 million people at international ports for infectious diseases over the past five years, officials said on Monday, while pledging to refine containment protocols that became a hallmark of Beijing's zero-COVID policy.

Customs officials detected more than 180,000 cases of infectious disease at China's borders during that time, Zhao Zenglian, deputy director general of the customs agency, told a news conference on border management.

Australia and Britain both warn travelers of possible medical checks upon arrival in China, even as Beijing seeks to revive inbound tourism and attract foreign investment to give its struggling economy a boost.

"Over 600 million inbound travelers and 300 million inbound vehicles and vessels were screened, and 5.25 million disease vectors were intercepted, effectively preventing the entry of over 30 types of vector-borne diseases," Zhao said.

He did not specify which diseases officials were screening for but since the pandemic China has warned of the risks posed by imported cases of mosquito-borne virus chikungunya and Mpox, a viral infection marked by flu-like symptoms and pus-filled lesions.

"Quarantine defenses at ports of entry have become more robust... Health and disease control departments have coordinated to build a 'closed-loop' management system: from overseas, to the border, and then to the home," Zhao said.

China's strict zero-COVID measures, in place from early 2020 to December 2022, effectively sealed the world's No. 2 economy off from international travel. The few who did enter were swabbed at the border, quarantined in designated facilities, and then transported home for further isolation - inside a 'closed loop.'