Tavarez died Monday afternoon at Cohen Children's Medical Center in New Hyde Park, on Long Island, said Katharina Harf, co-founder of the bone marrow donor center DKMS.
Adriana Douzos, a spokeswoman for the long-running, Tony winning show, also confirmed the death but declined further comment.
Tavarez, who played the young lion Nala, had received an umbilical-cord blood transplant in August. The procedure was performed as an alternative to a bone marrow transplant. Her doctor, Dr. Larry Wolfe, said that a perfect bone marrow match for Shannon could not be found.
The search for a match was especially daunting because Shannon's mother is African-American and her father is Hispanic, from the Dominican Republic. For bone marrow transplants, minorities and those of mixed ancestry have a more difficult time finding good matches because there aren't as many people from those groups signed up as potential donors. Right now, 83 percent of African-American patients who need marrow transplants don't find matches after six months of searching, according to the National Marrow Donor Program, a nonprofit organization dedicated to helping patients receive transplants.
Tavarez was forced to quit the show in April. She beat out hundreds of other hopefuls last year to earn her spot playing Nala, the childhood pal and girlfriend of Simba, hero of "The Lion King." She split the role with another girl, performing four shows a week for six months.
Keys, Rihanna and 50 Cent campaigned to help Tavarez find a bone marrow donor, and cast members held bone marrow donor registration drives. Harf said the donor center registered 10,000 people as potential donors. Keys skyped with Tavarez while she was at the hospital, Harf said, and the singer, Rhihanna and 50 Cent urged their fans to sign up as potential donors.
Child performers from "The Lion King" and other shows also sold bracelets and key chains that read, "Shine for Shannon," to raise money to help pay for her medical bills.
"It's rare that you meet such a spirited girl at such a young age," Harf said. "She touched so many people to register. She was really, really a special girl."
"Shannon's bright smile, amazing talent, and courage will continue to inspire us in our efforts," the New York Blood Center said in a statement.