The new variant is the latest challenge facing the games, which have taken criticism over the lack of natural snow in the Chinese capital, the country’s human rights record, and tennis star Peng Shuai’s recent accusations of sexual assault against a former top leader of the ruling Communist Party.

At a daily briefing on Tuesday, Foreign Ministry spokesperson Zhao Lijian said omicron would “certainly bring some challenges in terms of prevention and control.”

China maintains some of the world’s strictest anti-virus travel restrictions and has said it will not allow overseas spectators at the games. Athletes, staff and journalists will be confined to bubbles for the duration of the competition, which will take place at three far-flung locations in downtown Beijing, its suburb of Yanqing, and neighboring Hebei province.

Politicians, the WTA and leading tennis players have also raised concerns about the safety of three-time Olympian and former top-ranked doubles player Peng, who publicly accused Zhang Gaoli, a former member of the party’s Politburo Standing Committee of coercing her into sex three years ago.