The specter of COVID-19 has already reared its head before the Tokyo Olympics have even officially started.
A host of athletes and other members of Olympic delegations have tested positive leading up to Friday's opening ceremony, either putting their Olympic hopes in doubt or dashing them altogether by resulting in them withdrawing from the competition.
The Tokyo Olympics, which were postponed a year due to the pandemic, come amid rising infection rates in Japan, which has vaccinated only about 32% of its population as of July 29, according to Reuters.
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Here is a list of all the athletes who have tested positive, led by the most recent.
Aug. 3 - There were 18 new cases, including one athlete, a Greek artistic swimmer. The total is 294 cases.
July 29 - An additional 24 people accredited for the Tokyo Games have tested positive for COVID-19, Olympic organizers said, bringing the total number of accreditation holders to 193.
July 28 - U.S. pole vaulter Sam Kendricks tested positive for COVID-19 and withdrew from competing in the Games, the U.S. Olympic committee said.
An additional 16 people at the Games tested positive earlier in the day.
July 27 - Tokyo Olympics organizers reported seven new Games-related COVID-19 cases, including two athletes who were not identified.
July 26 - Tokyo's Olympic organizing committee reported 16 new positive tests. Of those, three were athletes, all staying outside the Olympic Village.
July 24 - American golfer Bryson DeChambeau tested positive for the coronavirus, the PGA Tour announced. He will be unable to compete for the U.S., and Patrick Reed will replace him.
July 23 - Three more athletes tested positive on the day of the Olympics' opening ceremony, according to a running tally of positive COVID-19 cases among athletes provided by Tokyo 2020. The athletes' identities were not specified.
July 21 - Czech Republic table tennis player Pavel Sirucek tested positive for the coronavirus, Kyodo news agency said.
U.S. men's beach volleyball player Taylor Crabb tested positive and will not be able to compete.
Dutch skateboarder Candy Jacobs said she tested positive for COVID-19 and cannot participate in the Games.
A Chilean female taekwondo player planned to withdraw from the Games after testing positive for the virus, Japan's public broadcaster NHK reported.
Olympic organizers said eight people, including an athlete who is not a resident of Japan and six contractors, tested positive for the coronavirus. The name, nationality and other details of the athlete was not given.
July 20 - Nine people, including one athlete staying at the Olympic Village, tested positive for the coronavirus, organizers said.
July 19 - Kara Eaker, an alternate on the U.S. women's gymnastics team, tested positive and another alternate was a close contact, USA Gymnastics said. How she contracted the virus is a "mystery to us," her father said on TODAY.
July 18 - U.S. women's tennis star Coco Gauff announces on social media that she has tested positive and will sit out what would have been her first Olympics.
South African soccer players Thabiso Monyane and Kamohelo Mahlatsi also tested positive along with a video analyst and a rugby coach, according to Team South Africa.
July 16 - Australian tennis player Alex de Minaur tested positive for COVID-19 before his departure for Tokyo, the Australian Olympic Committee said.
July 15 - Eight athletes from the Kenya women's rugby team were classified as close contacts after a positive coronavirus case was found on their flight to Tokyo, said an official with the southwestern city of Kurume, where they were set to hold a training camp.
U.S. basketball player Bradley Beal’s Olympic dream was cut short when USA Basketball announced he will miss the Games after entering coronavirus protocols at the training camp in Las Vegas.
An Olympic athlete under a 14-day quarantine period tested positive for the virus before moving to the Olympic Village, the organizing committee reported, without giving details.
July 14 - Twenty-one members of the South African rugby team isolated after they were believed to have been in close contact with a case on their flight.
July 9 - One Lithuanian and one Israeli athlete tested positive, according to reports. Later reports said the Lithuanian's results were unclear and subsequently tested negative.
July 4 - A member of Serbia's rowing team tested positive on arrival. The other four team members were isolated as close contacts.
June 23 - A Ugandan athlete tested positive, according to Izumisano officials.
June 20 - A coach with Uganda's squad tested positive on arrival at Narita airport and was quarantined at a government-designated facility. The rest of the team headed by bus for their host city, Izumisano, near Osaka in western Japan.