Amanda Seyfried was suffering from "a tough case of Covid" when she received her Oscar nomination earlier this year.

The Mamma Mia! actress scored her first-ever Oscar nomination in March for her portrayal of Marion Davies in David Fincher's Mank, and while it was an "amazing, career-changing" moment, it was also "one of the worst" because she was very sick.

"I turned my phone off the night before because I was like, if anyone's going to tell me I got an Academy Award nomination or didn't, I want it to be my mother, who lives with us. But I was also sleeping in because I had a tough case of Covid," she revealed during an appearance on Late Night with Seth Meyers.

The 35-year-old explained that she kept her Covid-19 diagnosis under wraps during the press interviews nominees have to do as she didn't want her illness to make headlines on nominations day.

"It was really hard to not talk about it... and I was like, (feigning sick voice) 'Yeah, no, I'm really happy, it's like really exciting, I couldn't be happier, really,'" she recalled. "I'm like so ill and I didn't want that to take over, you know, clickbait and stuff like that."

She continued, "So I was dealing with one of the worst moments of my life, worrying that my mum was going to get sick - she had been vaccinated, thank God - it was scary because I have two small kids and I was worried about them and my husband was working and it was really stressful and all of a sudden, this amazing, career-changing thing happens."

The actress, who shares two children with husband Thomas Sadoski, also revealed that she had been vaccinated two days before testing positive, and she joked, "It's great to have both, apparently. Hybrid immunity."