King Island's multiple national record-holder faces a race against time with both events less than two months away.

Since contracting COVID in January, McSweyn has struggled to regain the form which had seen him set four national middle-distance records, contest the 5000-10,000m double at the 2018 Commonwealth Games and make his Olympic debut in Tokyo.

After failing to finish a 5000m in Melbourne in March, he trailed home in 1500m Diamond League races in Doha and Birmingham last month well short of his 3:29.51 personal best.

"It has not been great but hopefully I can still turn it around," he said.

"It is frustrating with world champs and Commonwealth Games this year so I want to be right. But I'm staying hopeful that I can feel a lot better and I'm pretty optimistic that I can come good."

Speaking from his base in London, McSweyn said his health issues are dictating his schedule as the world champs (in Oregon from July 15 to 24) and Commonwealth Games (in Birmingham from July 28 to August 8) near.

McSweyn, who was vaccinated before the Olympics, had a booster shot in February.

"COVID affects people in different ways and there are different strains. I've really struggled with breathing and my heart rate. I've been trying to ride the wave to turn it around. Maybe it's because I have asthma as well. That might have been a factor.

"In training I don't feel a higher level of fatigue but I do in races. When I went to go really hard I noticed that I had absolutely nothing in the tank."

"I would race as normal, which is pretty aggressive, then get to halfway and have absolutely nothing left.

"I'm usually OK until the last few hundred metres but instead I'm struggling with breathing."

Still holding national records at 1500m, one mile and 3000m, McSweyn would target the shorter distance if given the opportunity at either upcoming event.

"Most likely my focus will be on 1500m because I have not trained as consistently or near the normal volume and that would be my first choice for both events anyway but it's all still up in the air.

"Luckily the window was open last year so I have a lot of qualifying performances from then, but I'd still like to put another one in to know I'm back feeling good.

"If I feel I'm training at a better level I will look at one of the European races whether that's Diamond League or something else. I wanted to get back to full health before having a crack at some more.

"But I have no timeline. It's a case of wait and see."

Having largely avoided serious injury through his athletics career, McSweyn, who turned 27 last week, has been frustrated by the issues and grateful to his support network.

"I've barely missed a race in the last few years so it is frustrating but I'm trying to stay optimistic and hope it all comes together.

"It's annoying because everything is so up in the air and there are not too many direct answers.

"I've been training easier while getting tests and stuff done to work out a plan of action to build back up.

"Hopefully I'll be racing before before the world champs then, fingers crossed, I can improve. Hopefully, in the next month or two, I can start to feel better.

"I think I've been really lucky with the support I've had. My coach and family, Athletics Australia and the Tasmanian Institute of Sport - they've been awesome throughout. When things are going well you don't need them as much, but when things go wrong they are the first people you need."