SEOUL - About 100 South Korean athletes and coaches travelling to Tokyo for the Olympics this year will receive their first doses of COVID-19 vaccine on Thursday, as the country struggles to keep its inoculation drive on track amid supply shortages.

Roughly 500 others will be vaccinated by the first week of May, before they travel to Japan, the Korean Sport and Olympic Committee (KSOC) said. Overall, more than 900 people from South Korea's delegation will be vaccinated.

Of those, 598 athletes and coaches will receive Pfizer's COVID-19 vaccine, which requires a shorter interval between doses – two to three weeks – and is less likely to affect their performance than the AstraZeneca shot, which will be provided to administrative staff as long as they are older than 30, the KSOC said.

The Games, pushed back by a year due to the pandemic, are set to run from July 23-Aug. 8 in Tokyo.

Organisers of the Tokyo 2020 Olympics rolled out stricter coronavirus countermeasures on Wednesday, including a plan to test athletes daily, as they try to reassure a Japanese public made increasingly sceptical by the resurgent pandemic. 

COVID-19 vaccinations are not mandatory for participation in the Olympics, but are recommended.

South Korea on Thursday said coronavirus infection rates over the next few days would determine whether authorities adjust social distancing rules for upcoming weeks.

"Most of the transmission routes are from coming into contact with confirmed patients," Health Minister Kwon Deok-cheol told a COVID-19 response meeting on Thursday.

Kwon said the vaccination programme is picking up speed and reaffirmed the government's pledge to vaccinate 12 million people in the key groups, including frontline workers and the elderly, by June and reach herd immunity by November.

Nearly 2.7 million South Koreans out of a population of 52 million have received their first vaccine dose, bringing the vaccination rate to just above 4%, compared with a 41% rate in the United States.

South Korea reported 680 new COVID-19 cases as of midnight on Wednesday, bringing the total number of confirmed cases to 121,351, and the total number of deaths to 1,825.

(Reporting by Sangmi Cha and Josh Smith. Editing by Gerry Doyle) ((;))