Top Australian triathlete Matt Hauser is out of a Paris Olympics test event because of COVID-19.

It continues a turbulent few days for Triathon Australia, who parted with their head coach Joel Filliol ahead of the Paris races.

Hauser has enjoyed an outstanding season and was well-placed to secure an automatic nomination for Olympic selection by finishing in the top eight at the men's test event.

But a positive COVID-19 test has sidelined him for the race, which will be run on Friday night (AEST).

"This hurts now, but better now than later," Hauser said in a TA statement.

"(I'm) gutted but health is the priority, next opportunity to qualify in five weeks."

Hauser's next chance to confirm his Paris Olympics spot will be next month's world triathlon championship final in Pontevedra, Spain, where again a top-eight finish is needed under the TA selection policy.

The Tokyo Olympian has been the standout Australian ahead of the Paris Games, winning his first world championship series race this season and currently holding fourth on the championship rankings.

"This is obviously really disappointing for Matt to miss the Paris test event, but health always comes first," TA chief executive Tim Harradine said.

"Our team officials have been working with Matt and the team through our protocols to ensure everyone is fit to race and Jake Birtwhistle, Brandon Copeland and Luke Willian will all line up to represent Australia at this afternoon's Olympic test event in Paris."

The women's test event was held on Thursday night (AEST), with Natalie Van Coevorden the top Australian in 19th place behind British winner Beth Potter.

Jaz Hedgeland was 34th and Emma Jackson finished 49th.

Meanwhile, Filliol's departure ahead of the Paris races is part of TA's review of its high-performance regime.

"Through this review, we've identified that changes are necessary to ensure the program is sustainable in the long-term; to both enable Paris 2024 performance, and concurrently develop athletes for LA2028 and beyond," it said in a statement.

"Changes in the Olympic program have been made as part of the review including the unwinding of the podium centre and the Olympic program head coach role, held by Joel Filliol, has been made redundant.

"Further changes in our performance team will be announced following Paris events.

"We thank Joel for his time with Triathlon Australia and wish him well moving forward."

Filliol, an international triathlon coach, referred to his departure from TA in a social media post on August 10.

"Reflecting on my final few days with Triathlon Australia - I am delighted to now be free to resume my work in the best way I know how," he said.