Timeline: Coronavirus outbreaks at the Tokyo Olympics

Despite strict measures, several Covid-19 cases have emerged among athletes and others involved with the Games

Police officers at a security checkpoint at the entrance to the Olympic Village that was opened on Tuesday, July 13, ahead of the Tokyo 2020 Games in Tokyo.

Police officers patrol outside the Olympic Village ahead of the Tokyo 2020 Olympic Games.

A team official of Britain transports equipment at the Olympic Village in Tokyo on Tuesday.

Policemen walk past one of the entrances to the Olympic Village in Tokyo.

Main dining hall of the Olympic Village in Tokyo.

Netherlands' flags and banners are displayed at the Olympic Village.

A team official of Belgium walks towards a security checkpoint at the entrance to the Olympic Village.

A team official of Canada at the entrance of the Olympic Village.

Recyclable cardboard beds and mattresses for athletes at the Olympic Village.

Weightlifting equipment at the fitness centre of the Olympic Village.

Fever clinic isolation area at the Olympic Village.

The delayed Tokyo 2020 Olympics will be held under unprecedented conditions including tight quarantine rules to prevent the spread of Covid-19.

Despite those measures, however, several cases have emerged among athletes and other people involved with the Games.

Following is a list of cases:

June 20

A coach with Uganda's squad tests positive on arrival at Narita airport and is quarantined. The rest of the team heads by bus for their host city, Izumisano, near Osaka in western Japan.

June 23

A Ugandan athlete tests positive, according to Izumisano officials.

July 4

A member of Serbia's rowing team tests positive on arrival. The other four team members are isolated as close contacts.

July 9

A Lithuanian and an Israeli athlete test positive, according to reports. Later reports say the Lithuanian's results were unclear and subsequently tested negative.

July 14

A masseur for the Russian women's rugby sevens team tests positive, forcing the team into isolation for two days, the RIA news agency reports. Officials in Munakata, southwestern Japan, confirm one staff member was hospitalised and say none of the team members could be considered a close contact.

- The refugee Olympic team delays its arrival in Japan after a team official tests positive in Doha. The infected official is in quarantine without symptoms, with 26 of the 29 refugees set to remain in their Doha training camp.

- Seven staff at a hotel in Hamamatsu, central Japan, where dozens of Brazilian athletes are staying, test positive, a city official says.

- Twenty-one members of the South African rugby team are in isolation after they are believed to have been in close contact with a case on their flight.

Egyptian table tennis player Dina Meshref practices ahead of the Tokyo Summer Olympic Games at Tokyo Metropolitan Gymnasium in Tokyo, Japan.

US softball player Haylie McCleney trains at the Fukushima Azuma Baseball Stadium.

Japanese tennis player Naomi Osaka trains at the Center Court Ariake Tennis Park.

Great Britain tennis player Andy Murray practices ahead of the Tokyo 2020 Olympic Games.

Members of South Africa's Olympic football team work out ahead of the Tokyo 2020 Olympic Games in Chiba, east of Tokyo, Japan.

An athlete from Portugal practices for the skateboarding competition at the 2020 Summer Olympics, at the Ariake Urban Sports Park in Tokyo.

A Japanese softball player tosses the balls into a basket during a training session at the Fukushima Azuma Baseball Stadium ahead of the 2020 Summer Olympics, 2021, in Fukushima, Japan.

Germany and Australia hockey teams take part in a scrimmage match at the Oi Hockey Stadium in Tokyo, Japan.

The USA's beach volleyball team practice ahead of the Tokyo 2020 Olympic Games.

USA softball player Dejah Mulipola takes batting practice during a training session at the Fukushima Azuma Baseball Stadium.

Members of the Italian women's softball team warm up during a training session at the Fukushima Azuma Baseball Stadium.

Japanese tennis player Kei Nishikori during training ahead of the Tokyo Olympics.

A Japanese softball player bows before walking onto the field during the team's training session at the Fukushima Azuma Baseball Stadium.

Members of the Japanese women's softball team train at the Fukushima Azuma Baseball Stadium.

July 15

Eight athletes from the Kenya women's rugby team are classified as close contacts after a positive coronavirus case is found on their flight to Tokyo, says an official with the southwestern city of Kurume, where they were set to hold a training camp.

- USA basketball player Bradley Beal’s Olympic dream is cut short when USA Basketball announce 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 tests positive for the virus before moving to the Olympic Village, the organising committee reports, without giving details. It says one member of the Games personnel and four Tokyo 2020 contractors also tested positive.

July 16

Australian tennis player Alex de Minaur tests positive for Covid-19 before his departure for Tokyo, the Australian Olympic Committee says.

- A member of the Nigerian Olympics delegation is in hospital after testing positive at Narita airport, according to media reports. The person, in their 60s, has only light symptoms but was admitted to hospital because of their advanced age and pre-existing conditions, TV Asahi says, adding it was the first Covid-19 hospitalisation of an Olympics-related visitor.

- An Olympic-related non-resident under a 14-day quarantine period tests positive for the virus, the organisers say, without giving further details. Three Tokyo 2020 contractors, all of whom are residents of Japan, also tested positive.

July 17

Fifteen people test positive for the virus, organisers say, including the first case at the athletes' village - a visitor from abroad involved in organising the Games. The rest are two members of the media, seven contractors and five members of the Games personnel.

July 18

Ten people, including two South African male football players staying at the athletes' village, tested positive for the virus. This is the first time athletes have been found positive within the village. The others are one athlete under a 14-day quarantine period, one member of the media, one contractor and five Games personnel.

July 19

Three people - one member of the Games personnel, one member of the media and one contractor - tested positive for the virus. Twenty-one people in the South African footballdelegation are categorised as close contacts, following positive test results for two players. The number of close contacts is later revised down to 18.

Those identified as close contacts can still take part in competition if they are found negative in a test conducted within six hours of the start of their event.

An alternate on the US women's gymnastics team tests positive and another alternate is a close contact, USA Gymnastics say. They remain at the team's training camp just east of Tokyo.

July 20

Nine people, including one athlete staying at the Olympic Village, tested positive for the novel coronavirus. The other eight were a volunteer worker, a member of the Games personnel and six contractors.