Moderna's vaccine trial and clinical research were a part of the Vanderbilt University Medical Center's efforts to stop the virus.
Parton's donation is listed in the New England Journal of Medicine preliminary report showing that the vaccine is highly effective. The country star previously announced the donation on Instagram in April.
"My longtime friend Dr. Naji Abumrad, who's been involved in research at Vanderbilt for many years, informed me that they were making some exciting advancements towards research of the coronavirus for a cure," Parton said at the time.
"I am making a donation of $1 million to Vanderbilt towards that research and to encourage people that can afford it to make donations," she continued.
Parton has yet to respond to the news about the vaccine's efficacy. Parton became friends with Abumrad after she was treated at Vanderbilt in 2014 following a car accident.
Moderna said that the vaccine is 94.5% effective in preventing infection, according to interim data the company published on Monday. The news came after Pfizer said its vaccine has shown to be about 90% effective.