The Federal Government announced last month that Australian athletes and officials heading to Tokyo 2020 will be given priority access to COVID-19 vaccines.

An estimated 2,050 people nominated by the Australian Olympic Committee (AOC) and Paralympics Australia are set to be vaccinated prior to the Games.

Under the Australian Government's initial plan to administer the vaccine, most athletes would not have been able to receive it until the second half of 2021.

Vaccinations began earlier this month and swimmers had been expected to receive their second dose between May 31 and June 4.

According to News Corp Australia, swimmers had reported side effects from the first dose.

Swimming Australia and the AOC have agreed to push the second dose until after the swimming trials, scheduled for June 12 to 19, to avoid any potential impact on performance.

"We understand there's not a lot of implications with that second jab, but there's still kind of the possibility of some flu-like symptoms," Swimming Australia chief executive Alex Baumann told News Corp Australia.

"We did have conversations with the AOC about possibly moving that to after trials and we're appreciative."

Ian Chesterman, Australia's Chef de Mission for Tokyo 2020, said "we need to get things moving as quickly as possible to give it as much time as possible close to the last injection before they go to the Games".

"Swimming approached us about delaying that second shot until after their trials, which is fair enough and pretty easy to facilitate because they're all in one spot at one time so that's still the most efficient way," added Chesterman.

The Australian Olympic team travelling to Tokyo 2020 is likely to consist of between 450 to 480 athletes competing in more than 30 sports.

The Games is scheduled to take place from July 23 to August 8.

Several nations have either vaccinated or begun the process of vaccinating their athletes ahead of Tokyo 2020.

The International Olympic Committee (IOC) has expressed hope that a "significant number" of participants will have received the jab before the Games.

Vaccination is not mandatory to compete at the Games.

The IOC last week signed a deal with Pfizer, which will see the pharmaceutical giants donate vaccines prior to the event.

The Chinese Olympic Committee has also offered to vaccinate Tokyo 2020 and Beijing 2022 teams, with the IOC paying for the cost of each dose.

They will only be available in territories which have approved the Chinese vaccines for use, which will also be the case as part of the IOC's deal with Pfizer.

A similar move was made by the Russian Olympic Committee, who offered vaccines to the Association of National Olympic Committees of Africa.

The agreements have received criticism in some quarters, with some suggesting athletes are "queue jumping".