Protection from COVID-19 took another step forward in Pennsylvania and New Jersey Monday as residents at skilled nursing facilities became the first people outside of health workers to receive shots.

“Are you ready to make history?” Nadine Mackey, a CVS pharmacist giving injections at a Phoenixville rehabilitation facility for seniors, asked Lydu Trudeau as she pulled down the collar of her sweater to bare a shoulder for the vaccine.

“Oh, sure,” replied Trudeau.

The 76-year-old has been at PowerBack Rehabilitation for about two weeks, recovering from heart surgery. Patients there, 22 as of Monday, tend to be in their late 70s, and stay temporarily as they recover from circumstances ranging from surgeries to strokes, said Stacy Omar, executive director of the facility.

Across Pennsylvania on Monday, teams from CVS and Walgreens went to nursing facilities to administer the Pfizer-BioNTech vaccine. The vaccine will be available to residents at 126 skilled nursing facilities in Pennsylvania throughout this week, state health officials said. In New Jersey, nearly 300 long-term care facilities were expected to receive doses in the next six weeks, Gov. Phil Murphy said Monday.

Pennsylvania Health Secretary Rachel Levine said most residents and staff of nursing homes, which have been devastated by the virus since March, indicate they will opt to get the vaccine. Residents who suffer from dementia and Alzheimer’s, and who cannot provide consent for themselves, may be vaccinated if a loved one signs off on their behalf.

Nursing home residents account for 38% of the more than 320,000 COVID-19 deaths nationally, according to the COVID Tracking Project.

An advisory board for the Centers for Disease Control and Prevention has recommended all people age 75 and older be given priority in the next round of vaccinations, possibly as soon as January, due to their increased risk of death if they’re infected by the coronavirus.

About 80,000 people live in Pennsylvania’s 700 nursing home facilities, and Levine said more residential facilities will receive vaccine doses in January. The names of the 126 nursing homes receiving vaccines this week will be released in the coming days, she said.

PowerBack Rehabilitation had 75 doses Monday, enough for about 90% of residents and staff, Omar said. Those not vaccinated Monday would receive their first shots on Jan. 18, when CVS staff returns for a second clinic.

» READ MORE: First COVID-19 vaccine doses come to Pennsylvania

Trudeau, a native of Colombia, expected to return to her home in West Chester by Thursday. She was ready to leave the facility where COVID-19 restrictions meant her three children and four grandchildren couldn’t visit.

But her departure highlighted one of the many challenges of the vaccination process: ensuring that people come back for their second shots.

Both the Pfizer and Moderna vaccines require two shots spaced about 21 days apart. Unlike health-care workers and long-term care facilities’ residents, who are likely to still be working or living in the same place three weeks after their first dose, most of the people staying at the Phoenixville facility Monday probably won’t be there when they’re due for their second shots.

“The documentation involved with everyone getting the shot is very, very lengthy and in-depth,” said Gary Bernett Sr., a doctor and vice president of Genesis Physician Services, which operates PowerBack.

The facility has conducted Zoom calls with patients’ families and made physicians available to answer questions in an effort to ensure that people understand their vaccination isn’t complete after one shot, Bernett said. In cooperation with CVS, they are also keeping detailed contact information for every patient who received a shot Monday so they can be reminded to return for a second dose on Jan. 18, he said.

“She may come back here,” he said of Trudeau, “or line up in the hallway, or we’ll go out to her car.”

The Garden State’s first long-term care resident to be vaccinated was 103-year-old Mildred Clements of the Roosevelt Care Center, in Old Bridge.

”She was born the year before the flu pandemic of 1918, and today, more than a century later, she was vaccinated against the current pandemic,” said Murphy, who visited the center to witness the vaccinations Monday morning.

Nursing homes have largely had to create their own plans to keep track of people who have received a first dose, Bernett said, receiving little guidance from state or federal health officials in a process that is already turning into a logistical mess. Health officials said for months that the record-keeping needed to ensure people get their second doses, and receive the right dose of the two vaccines available, will be one of the most complicated aspects of vaccination. Local and state health officials have described vaccination distribution planning as a work in progress, and have said uncertainty over how many doses will be available even just a week from now has complicated efforts.

At PowerBack Rehabilitation, staff waited for doses alongside residents Monday. Gloria Campbell, 55, a registered nurse who began working there in August, received the first shot. She was relieved but echoed a common sentiment among health-care workers: that the precautions they’ve learned over nearly a year of treating people during a pandemic have built confidence they can work safely even without a vaccine. For the time being, she said, she’ll continue wearing a mask and face shield.

“Actually, nothing much has changed,” Campbell said.

This week, 47,775 doses of the Pfizer vaccine are scheduled to be delivered to Pennsylvania hospitals, Levine said, as are 26,100 doses of the Moderna vaccine. These numbers do not include vaccinations that have be given in Philadelphia, which has its own vaccine allotment.

» READ MORE: COVID-19 vaccine gives Philly health-care workers a glimpse of pandemic hope. Then it’s back to work.

After skilled nursing facilities inoculate residents and staff, the vaccine rollout will reach other long-term care locations, such as personal care homes, assisted living facilities, residential treatment facilities, and congregate homes for people with developmental disabilities. The commonwealth will release a plan this week to ensure home health-care providers get vaccinated in this first round, Levine said Monday, and officials are updating their plans for the next vaccine priority group — essential workers and people 75 and older — that could begin receiving doses next month.

“What’s still clear is the vaccination process will take us some time,” said Levine, who estimated the general public won’t be vaccinated until late spring or early summer. “In the meantime, our current mitigation efforts are more important than ever.”

Staff writer Ellie Rushing contributed to this article.