"Dancing With the Stars" pro Cheryl Burke revealed in an emotional Instagram video on Sunday that she tested positive for COVID-19 despite being vaccinated.
The 37-year-old dancer, who is paired with Peloton instructor Cody Rigsby, detailed her journey getting tested in the morning and learning the results of her breakthrough infection just one day before the live competition show was set to tape a new episode on Monday.
"The PCR test came back, and it came back positive," she said. "I feel so bad for Cody. I feel like I'm letting him down. I just feel like s---, to be quite honest. And it's so overwhelming because it's Sunday, and the show's tomorrow."
She continued: "I figured I should let you guys know since I've been as open and as real and vulnerable as I could be here. I just hope I didn't spread it. For those of you who don't think Covid is a real thing, it's f------ real, dude."
It was unclear if Rigsby would perform with a different person. ABC did not immediately respond to a request for comment Monday.
Burke said she was "fully vaccinated" with the two-shot Moderna vaccine. Breakthrough infections do not mean vaccines are not working. They are expected because no vaccine is 100% effective, according to experts. However, data shows severe breakthrough infections are rare.
In a study published by The Lancet Infectious Diseases this month, researchers in the United Kingdom analyzed data from a project called the ZOE COVID Study, where users report symptoms, vaccination status and other demographic information daily via an app.
The researchers looked at data collected on more than 1 million people from December 2020 through July 2021, a period that spanned both the alpha and delta variant waves in the U.K. Participants received two doses of either the Pfizer-BioNTech, Moderna or AstraZeneca vaccine.
Overall, less than 0.2% of the participants reported a breakthrough infection, with such cases more likely in people already considered to be vulnerable, including older adults or people with underlying illnesses.
When breakthrough infections did occur, most were mild — just 6% of people with breakthrough infections reported symptoms. What's more, vaccination was shown to cut the risk of hospitalization by more than two-thirds. The study also found that the chances of developing long COVID were cut in half in fully vaccinated people. Long COVID refers to when people experience symptoms of the illness, such as brain fog, exhaustion and a racing heart, for at least a month after infection, and sometimes much longer.
Two other studies published this month also found an extremely low rate of breakthrough infections.
The first, published in JAMA Network Open, analyzed breakthrough infections among more than 5,300 vaccinated health care workers in Israel. Just 27 such infections were found. No deaths were reported, and just one patient required hospitalization. The study, however, was completed prior to the delta variant becoming the dominant strain in Israel.
The other, published in the New England Journal of Medicine, detected 94 symptomatic breakthrough infections out of more than 16,000 health care workers. That study, which ran through July, found that breakthroughs increased as the delta variant grew dominant.
In her video, Burke said she would have to quarantine for 10 days.
"I've been ordered to stay home," she said. "I'll be in bed. I can't believe this happened."
This article was originally published on NBCNews.com.