Swimming Australia (SA) hopes its Olympic team will receive COVID-19 vaccines before the Tokyo Games but must prepare for the scenario that they miss out, the governing body's newly appointed Chief Executive said on Thursday.

Australia has restricted the roll-out of its favored AstraZeneca vaccine to people under 50 over blood clotting concerns, slowing the national vaccination program further after the European Union blocked exports to the country. The sluggish roll-out has raised concerns that the Australian athletes could miss out on vaccines, even as rival nations race ahead with inoculations for their Olympians before Tokyo.

"We have to prepare for the worst. We have to prepare that the athletes won't be vaccinated," SA CEO Alex Baumann told reporters at the national championships on the Gold Coast on Thursday. "But it really is a choice for the athletes. We're not going to make it compulsory. Obviously, it would be preferable to have the athletes vaccinated. We'll encourage that."

Australia said on Tuesday a second person had been diagnosed with a blood clot after receiving the AstraZeneca vaccine. Australian authorities recommend people who receive the first dose of the AstraZeneca vaccine have a booster after 12 weeks to maximize immunity.

The opening ceremony for the Tokyo Olympics will be held on July 23. Baumann and SA President Kieren Perkins said no swimmers had approached them with concerns about vaccinations or the narrow time frame to have them before Tokyo.

Perkins said he would not want to influence athletes on their decision to have vaccines if they became available but said he would gladly take the AstraZeneca shot. "As an Australian citizen who is under 50, I've seen the stats and I don't have any problem taking the AstraZeneca vaccine myself," the 47-year-old former Olympic champion told reporters.

"From the minute that I'm able to, I'll be lining up at the door and going in to get it."