ORLANDO, Fla. — Citing “very exciting times” amid the distribution of one COVID-19 vaccine and the development of another, AdventHealth said Tuesday that several thousand front-line health care workers at its Orlando and Celebration facilities had signed up for vaccinations and that it would start administering the shots Wednesday.

The health care system said it would keep 9,400 of the 20,000 Pfizer doses it received Tuesday and would share the rest with systems including HCA, Orlando Health, and Nemours Children's Hospital.

Officials said they would send any unused doses outside the area of Orange, Seminole, and Osceola counties, including to Daytona Beach and Lake County.

As for its own workers, AdventHealth said it would prioritize vaccinations based on risk of exposure to COVID-19, starting with workers in intensive care, COVID units, and emergency departments, among other areas.

Dr. Neil Finkler, AdventHealth’s chief medical officer for acute-care services in Orange, Seminole, and Osceola counties, touted the safety and efficacy of the Pfizer vaccine and of the coming Moderna vaccine. He said he expects government emergency-use authorization for the Moderna vaccine as soon as Friday.

“Very exciting times,” Finkler said Tuesday. “And really, at the end of the day, if you really think about the success of vaccines, and the promise that this has with regards to saving lives and actually getting us out of this global disaster, it’s staggering.”

He pointed out that AdventHealth isn’t yet requiring workers to get the vaccine but urged health care workers to get one as soon as it’s available to them.

“As a physician who has practiced medicine for nearly 40 years, I highly encourage all physicians, nurses, and our entire community to receive the vaccine when it becomes available to you,” Finkler said. “I personally will receive the vaccine when I'm able to, and I look forward to getting this done as quickly as possible.”

Finkler spoke Tuesday during a virtual news conference that included Linnette Johnson, AdventHealth’s chief nursing officer for acute-care services in Orange, Osceola, and Seminole counties.

AdventHealth is one of five Florida hospital systems that the state chose to distribute the Pfizer vaccine. As scheduled on Tuesday, it received about 20,000 doses from Florida’s reported allotment of about 180,000 doses in this first round of distribution.

Health officials point out that it could be some time before vaccinations become available to everybody.

Finkler and Johnson emphasized the safety and effectiveness of the vaccine and the extraordinary time in which it arrived. The coronavirus has killed more than 300,000 people in the U.S. since its arrival in March, and health officials are bracing for deaths and hospitalizations to continue climbing.

Johnson discussed the sacrifice of health care workers, plus the mental boost that the vaccinations could bring.

“We are so thrilled and excited about the vaccine,” she said. “It is the safest way for us to move forward and to keep our communities, our loved ones, our colleagues well, which is why we're encouraging that when the vaccine is available for all, that you receive the vaccine, and why it means so much to us as health care workers.”

She added: “There is nothing more frustrating than going to school for a long time to save lives and not being able to do it. This vaccine could be the game-changer for that.”

Finkler emphasized that people shouldn’t worry about getting COVID-19 from the vaccine. As he put it, the vaccine doesn’t contain the virus but the genetic code to create a protein to which the human body responds.

“It's a really novel way to do it,” he said of the vaccine. “And quite frankly, I believe that we're at the watershed moment of how we're going to look about how we treat things moving forward.”