Brian Cox has revealed he contracted coronavirus.
The actor, 74, said he believes he caught the deadly virus while working in London before Christmas, during an appearance on the Late Late Show on Wednesday.
Brian said he unknowingly carried the virus and only discovered he had the antibodies after visiting his doctor for a blood test due to his diabetes.
Discussing his experience with host James Corden on the programme, which is back in the studio for the first time since lockdown, Brian explained his main symptom was 'sneezing fits'.
Sneezing is not currently listed as one of the symptoms of Covid-19 and patients are typically told to look out for a high fever and continuous cough.
Brian, who recently bagged an Emmy nod for his role as media mogul Logan Roy, said: 'The problem is I never felt anything.'
'For about four days I had these sneezing attacks, just sneezing.'
'The doctor told me that three of her patients had also these (sneezing) attacks and that is an unknown symptom of COVID.'
Brian revealed he experienced the 'unknown' symptom after returning from London, where he had been directing a play with his wife Nicole Ansari-Cox.
He remembers also experiencing fatigue, however he revealed he put that down to the jet-lag from the trip.
Brian is among a host of celebrities who have spoken out about their experience including Tom Hanks, Idris Elba, Lena Dunham and Alyssa Milano.
The star recently detailed life in lockdown as he isolated in New York with his wife Nicole and their two sons, Orson, 18, and Torin, 15.
During a pre-recorded interview with Lorraine Kelly from his cabin in the Big Apple in May, Brian admitted he was finding homeschooling 'tough' as he's 'not at home a lot of the time'.
The screen star also said his beloved partner was 'making me stay at home' as he falls within the at risk category of those more vulnerable to COVID-19 due to his diabetes.
Brian, who was awarded the Best Actor prize at the Golden Globes, normally leads a particularly busy lifestyle, but has been forced into quarantine due to the coronavirus pandemic.
On teaching his two younger sons, the thespian confessed he was finding the process challenging.
The TV and film star said: 'They're difficult, not easy, it's tough for them. We have to do homeschooling.
'I have to get my young lad to bed as he's always up late on his video chats. I didn't expect this, a lot of the time I'm not here, so fatherhood has been thrust upon me late in life.'
Showing the presenter around his cabin by panning his laptop, Brian, who also shares daughter Margaret and actor son Alan, 49, with ex-wife Caroline Burt, insisted he was making sure he's taking extra precautions to stay safe.
He explained: 'I'm in a rural environment, my house is down by the trees. I have diabetes so I'm high-risk, my wife makes me stay at home, make sure you wash your hands!'
The Scotsman also expressed his gratitude towards the NHS, stating: 'I've been here in NY for ten weeks. Without the carers, we'd be lost. We have to make sure their stress is reduced to the minimum.'
The media personality has achieved critical acclaim for his portrayal as media magnate Logan Roy in HBO's Succession.
On whether the show's third series will go into production in the coming months, a coy Brian said: 'It's grown. The first series was great, the second was fantastic.
'If we get the third series... well I'd have to kill someone if I told what will happen as they always keep it top secret.
'I'm not sure if COVID will come into it, are we going to refer this period that we've got now, or are we going to recognise it? There's a paradigm shift between stuff that's live and what you can watch now.'
The father-of-four is currently starring in an online pilot episode of Little Room – a murder mystery series filmed during lockdown.
On filming the show from his home, Brian said: 'I'm locked into just doing that, I'm owned by HBO, I had no idea it was just an online pilot. I'm getting my wife to talk for me as I'm too shy haha.'
The pilot was created with the purpose of raising money for film and TV freelancers in the UK and the US.
© Associated Newspapers Ltd.