Angelina Jolie delivered a message to fans Friday explaining why she wouldn’t be able to attend the premiere of her newly directed movie Unbroken. Due to the highly contagious nature of the disease, she is required to stay home and away from others to avoid spreading the characteristically red and itchy bumps.

"I just wanted to be clear and honest about why I will be missing the Unbroken events in the next few days, which is that I found out last night that I have chickenpox,” Jolie said in a video published to Universal Studios Entertainment's verified Facebook page on Friday. “So, I will be home itching and missing everyone. And I can't believe it because this film means so much to me. I just can’t believe it. But such is life.”

The 39-year-old actress directed the film based on the true story of American World War II hero and track Olympian Louis Zamperini. He recently died in July at the age of 97. However, his family members will still attend the premiere as Jolie’s special guests. The film is set to release in theaters on Christmas Day.

Every year, approximately four million people get chickenpox, and between 100 to 150 people die because of it. It’s currently unknown where she caught the chickenpox from, but it is a predominantly childhood illness. Chickenpox has become a common and often normal part of a child’s life, which is why many people forget it’s a disease. They cause blister-like rashes, itching, tiredness, and fever.

Children almost always recover, but the condition can be significantly worse if babies, adolescents, adults, pregnant women, or those with weak immune systems contract it, according to the Centers for Disease Control and Prevention. After a person recovers from chickenpox, it lies dormant in the body at the roots of nerves and can reactivate many years later. Researchers aren’t entirely sure why it reawakens in some people, but they believe it could be triggered by a weak immune system or chronic stress.

After directing a film at the caliber of Unbroken, it’s no surprise Jolie was plagued with stress enough to lower her immune system, giving the dormant disease a chance to spread again.