The long-feared possibility that the Covid-19 pandemic could disrupt the Tokyo Olympics is rapidly emerging as a reality, as Games organizers scramble to deal with a rising load of athletes and officials who are testing positive upon arrival in Japan. 

The stream of positive cases is quickly demonstrating how difficult it will be to stage one of the world’s largest events during a global pandemic. Tens of thousands of participants from more than 200 countries are entering a country where the vaccination rate of the local population remains low and the more-contagious Delta variant is spreading. 

Officials have a dilemma that will run throughout the Games. The Japanese public is deeply wary of the Olympics, fearing an outbreak that will spill into the general population. So they are deploying strict rules to limit the risk—which could block athletes from participating if they become ensnared in Covid protocols. 

The Games are also losing star power regardless of whether athletes ever make it to Japan. The 17-year-old U.S. tennis star Coco Gauff announced on social media that she has tested positive for Covid-19 and will miss the games. “It has always been a dream of mine to represent the USA at the Olympics, and I hope there will be many more chances for me to make this come true in the future,” she wrote. It was not immediately clear whether Gauff had traveled to Japan yet.