Athletes are being encouraged to get vaccinated against COVID-19 ahead of the Tokyo Olympics but it will not be compulsory, IOC Vice President John Coates said on Thursday.

"Not compulsory, we can't do that," Coates, head of the IOC's Coordination Commission for the Tokyo Games, told reporters in Brisbane.

"But it is certainly being encouraged and the IOC has an agreement with COVAX where it's helping to facilitate the distribution of vaccines."

COVAX is the World Health Organisation's global vaccine-sharing scheme.

IOC President Thomas Bach said last month it was up to national Olympic committees to coordinate with their governments over access to vaccines but he was not in favor of athletes "jumping the queue."

With the delayed Games set to begin on July 23, Coates, who is also president of the Australian Olympic Committee, expected the country's athletes to be vaccinated by June at "the latest."

Australia began its vaccine roll-out this week.

Coates also said Japan's government was expected to make a decision on how many fans could attend the Olympics by April.

Organizers hope to have spectators at the Games though speculation remains that the event might be canceled due to the COVID-19 pandemic.

"A decision on all of the accredited people and all of those who have bought tickets in Japan will certainly be there," he said.

"A final decision will be taken by the Japanese government, it's governments that decide these things on what's safe and, a bit later, probably March, April ... a decision on what venue capacity we are going to have."

Coates said officials had to make the Athletes Village and venues "the safest place in Tokyo."

"Last week we had four days of operational planning, we are down now to looking at the seating on the buses to make sure there's the correct distancing," he said.

"Well that's all very well, we suddenly need double the fleet of buses and there's a lot of buses involved."