BEIJING—China used coronavirus prevention measures, intimidation, and visa curbs to limit foreign reporting in 2020, ushering in a “rapid decline in media freedom,” the Foreign Correspondents’ Club of China (FCCC) said on Monday. For the third year in a row, no journalists told the group that working conditions had improved, the FCCC said in an annual report based on 150 responses to a survey of correspondents and interviews with bureau chiefs. “All arms of state power—including surveillance systems introduced to curb coronavirus—were used to harass and intimidate journalists, their Chinese colleagues, and those whom the foreign press sought to interview,” it said. Authorities cited public health concerns to deny reporters access to sensitive areas and threatened them with enforced quarantine, it added. Visa restrictions were also used to put pressure on reporting. At least 13 correspondents were given press credentials valid for 6 months or less, the FCCC said. Foreign …