BALTIMORE (AP) — Maryland's first doses of the new COVID-19 vaccine arrived Monday at two Baltimore hospitals as health care workers at one of the facilities began to get inoculated.

A shipment of the Pfizer-BioNTech vaccine arrived at the University of Maryland Medical Center, where two physicians, a nurse, a respiratory therapist and an environmental service worker received their first of two required doses. On Monday evening, Johns Hopkins Medicine announced that it has received its initial doses and expected to administer vaccine to frontline workers beginning on Wednesday.

Video provided by the University of Maryland Medical Center shows employees carefully opening a shipping box, taking out a small container and placing it inside a freezer with a temperature reading of minus 112 degrees Fahrenheit (minus 80 Celsius). Joseph DiCubellis, the system’s senior director of pharmacy services, called it a “historic moment.”

In a news release, the system said it received one tray of 975 doses. More inoculations are expected later this week.

“I am a nurse on the frontlines of caring for COVID patients and I believe in the science behind the vaccine,” Shawn Hendricks, the center's nursing director of medicine, cardiac services and tele-sitter program, said in a statement. “I want my family and I to be safe from getting COVID. Unless people start to get vaccinated, I think this pandemic will last longer, and get worse.”

Hendricks oversees units with patients sickened with the coronavirus. Her mother, brother and brother-in-law were previously diagnosed with the virus. Her mother's recovery lasted two months.

The statement from Johns Hopkins Medicine also said it's developed a plan for the order in which the vaccine will be administered.

“Clinical and non-clinical staff members essential to delivering care and support services to patients with and without COVID-19 will be the first to be offered the vaccine through a random selection process,” according to the statement. “The vaccine will not be mandatory for our employees.”

Maryland will focus its initial COVID-19 vaccinations on hospital-based health care workers, residents of nursing homes and first responders. The state is expected to receive 155,000 initial doses. That figure includes 50,700 Pfizer doses and 104,300 Moderna doses.

Dr. Jinlene Chan, the acting deputy secretary of Maryland’s health department, earlier this month said the state will expand access to the vaccines when more doses become available.

State health officials have issued an emergency order to expand the scope of practice so that any licensed health care provider — including doctors, nurses, paramedics, and pharmacists — can administer the COVID-19 vaccine with appropriate training and supervision. It could be months before the general public has access to a vaccine.