star Jessie Cave has said it was a "scary start" for her newborn baby after he tested positive for coronavirus.
The actress, best known for her role as Lavender Brown in the film adaptations of the hit books, welcomed Tenn in October after a "traumatic" delivery that left him in the neonatal unit.
She has since confirmed the baby is out of hospital and is doing well but her partner now has Covid-19 and the stress of the ordeal caused her breast milk to dry up.
Cave, 33, told ITV's Lorraine: "Nothing has gone to plan, which I guess everyone can relate to this year. It was a really scary start.
"He was in the neonatal unit after a really sudden, quick labour. He came out within 45 minutes, so he was just a bit like, 'What's going on?', and was taken to the neonatal unit.
"He's 11 weeks now. I couldn't believe it when we found out! But I almost can believe it as it's been such a strange period of time for everyone but (it was) very scary."
Discussing how Tenn may have contracted the virus, she continued: "All I know is it's absolutely the most contagious thing. I was completely symptomless, so it's just bizarre. I did go and get a test because I wanted to see my mum and family at Christmas, and then obviously we couldn't.
"They have to be aware of a sudden quick change, because it could have been a completely different story if I hadn't gone in."
She added: "Everyone is so scared right now, understandably... but you really do have to be so quick to go in and don't be scared of going in... just don't wait, go!"
Cave and her partner, comedian Alfie Brown, are already parents to Donnie, five, and Margot, three, and Cave said Brown now also has the virus.
She said: "It's just a weird delay. It's such a strange illness and it affects everyone completely differently and so it's completely affected our lives over this period of time. I can't really imagine a normal day now.
"He is OK, he's doing much better now. It's just bizarre how it didn't affect me and it's completely affected him. We know people who have had to go to hospital. It's a lottery really. It can affect you and you never expected it."
She added: "My brother is an A&E doc and my dad's a GP who runs a coronavirus hub and now a vaccination hub. Listening to them it's amazing how much worse it is this time. We've all got relaxed in a way because we are so used to lockdown and to the restrictions but having the virus now and having time in hospital is a completely new chapter for me.
"Everyone has said to me, 'I didn't think babies can get it' but it can affect everyone.
"The other thing is with this stage of newborn, their immune system is so weak, and so anything can have really bad consequences. That's why they treated it so seriously, even my breastfeeding was completely affected by this, even two nights of a change of routine has affected us.
"Because of the stress my milk dried up a little bit and now I've had to give him formula and so our entire lives have changed, just two nights can affect your entire lives for a bit."