The couple are unable to proceed in the competition as the Olympic boxer will now have to self-isolate for two weeks while her professional dance partner recovers.
In a statement, Strictly bosses revealed Katya is asymptomatic, adding: “As part of the protocols outlined ahead of the series, this sadly means they will no longer be able to take part in the competition.”
Nicola, who was part of the show’s first-ever same-sex couple alongside Katya, said: “I’m absolutely devastated my Strictly journey has come to an end so soon. I had so much more to give and so many people to win this for! But I just want to say a huge thank you to Katya for being the best dance partner anyone could ask for. She pushed me way out of my comfort zone and it’s been an incredible experience.
“I’m gutted to be out of the competition but in these unprecedented times and as frustrating as it is, the Covid measures in place are to keep everyone safe, and I’m doing what I can to help.
“I’ll be spending the next 14 days isolating so I’d like to apologise in advance for the ridiculous amount of TikToks I’ll be posting, in my new found free time when I’m not gaming!”
Prior to the series, Strictly bosses had warned stars that they would be axed from the show if either person in their pairings tested positive for the virus.
Strictly rules have always allowed injured or sick stars a one-week bye in previous years, but the two-week isolation period means that contestants forced to quarantine would be out of the competition for too long.
Katya added: “Dancing with Nicola has been an absolute inspiration. She’s given her all each and every week and we were so excited to create more dances in the competition.
“Of course, I’m devastated to leave this way but I’ve made a friend for life and loved every moment of this special journey. I’d like to wish good luck to all the remaining couples!”
Strictly’s executive producer, Sarah James, also said she was “hopeful that there will be opportunities for them to dance again in the future”, hinting the pair could return next year.
“They are a brilliant partnership and had already achieved so much during their time on the show,” she added.
The BBC has confirmed the rest of the cast are unaffected and the show will continue on Saturday as usual.
However, according to the PA news agency, a number of Strictly crew members are also self-isolating after coming into contact with Katya.
Meanwhile, It Takes Two presenter Rylan Clark-Neal has also been forced into self-isolation after coming into contact with someone who has the virus outside of work, meaning he will miss two weeks of hosting the spin-off show.
Strictly Come Dancing airs on Saturday at 7.10pm on BBC One.