Who gets the COVID-19 vaccine next, and when? Pa. and N.J. are working on it.

While the nation waits to see whether the holidays will lead to a new surge in coronavirus cases, the region was focused Monday on who will get the vaccine and when.

More than 100,000 doses have been administered since late last month in both New Jersey and Pennsylvania, with thousands more health-care workers and nursing home residents set to get shots this week.

But more questions than answers remained as the two states and Philadelphia continued preparing for expanding access to inoculations. Facing a massive logistical challenge — and amid national concern about the pace of the process — officials in all three spots said Monday they were still working on plans to determine how to distribute the vaccine in the next phase.

How quickly the states can act — and how soon the general public gets to line up for shots — depends largely on how many doses can be produced by manufacturers and then distributed by the federal government. Pennsylvania Health Secretary Rachel Levine predicted on Monday that with the holidays over, the effort will ramp up nationwide.

» READ MORE: Vaccinations are ramping up in a ‘glimmer of hope,’ Dr. Anthony Fauci says

Only frontline health workers and nursing home residents and staff are currently eligible to be vaccinated in Pennsylvania and New Jersey. In the next round of inoculations, the shots will likely go to people 75 and older and various types of essential workers.

Pennsylvania and Philadelphia officials said it was too soon to say exactly how that will roll out. In New Jersey, some residents could be able to make online appointments for the vaccine within “a couple of weeks,” state health officials said, though officials are still assessing who will be in that group.

“Primary care doctors and specialists are getting multiple calls a day from patients who want to know when they can be vaccinated,” said Temple University Health System chief medical officer Tony Reed.

States are receiving a different number of doses each week, and the delivery schedules also fluctuate, another challenge that slows distribution, Levine said. She also said funding from the federal government will be key: Pennsylvania needs money allocated to states in the latest stimulus bill to staff the mass vaccination clinics it plans to open.

Public health officials have estimated it will take months before the general public is vaccinated. Levine advised people to be patient; follow public health guidance; stay in contact with their doctor, if they have one; and follow the news and updates from the health department.

A few indicators Monday suggested the spread of the virus had slowed slightly in Pennsylvania and New Jersey, but lags and irregularities in reporting cases and deaths are expected over the next several days as a result of the holidays. Pennsylvania officials did not have an accurate picture of the number of people newly infected over the weekend because of database maintenance.

At least 162,000 Pennsylvania health workers have received first doses, though that represents fewer than half of the vaccines allocated to the state so far. Shots have also been given out at more than 100 nursing homes, but the state does not know how many people in those facilities have been vaccinated because the data go to the federal government, which has not yet shared the numbers.

The state is in line to receive more doses this week: 166,725 of the Pfizer vaccine and 80,000 of the Moderna vaccine. Just over half of the Pfizer shipment will be second doses for health-care workers who received their first shots last month, Levine said. The state is also working on vaccinating nonaffiliated health-care workers who can’t get the shot through an employer.

The state is working on plans for mass vaccination sites and an appointment sign-up system, but officials did not have details Monday. Levine said officials did not yet know when the frontline workers and older adults who will be eligible next would begin getting shots.

“I wouldn’t say we’re far behind,” Levine said of the state’s pace. She said the state was “working to ramp up” distribution to the first priority group, designated 1A. “When we come to when 1B will start, I promise you we will be ready.”

» READ MORE: These are the current Pennsylvania coronavirus guidelines

Of New Jersey’s approximately 400,000 doses, about 101,000 were reported to have been administered, but the actual number may be higher due to a lag in reporting, Gov. Phil Murphy said. An additional 120,000 doses were set aside for long-term care facilities.

On Monday, the state started giving second shots to health-care workers who got the first doses last month. Two vaccination “megasites” will open Friday, one in Gloucester County, Murphy said; for the time being, only health-care workers will be able to receive shots there. Shots will also eventually be administered at about 200 locations, including hospitals, pharmacies, primary care offices, and urgent-care centers.

Philadelphia officials said it was too early to say how the distribution process in the city will work. Because it has to apportion limited doses, the city — like states and other jurisdictions across the country — is grappling with questions including which essential workers should be vaccinated first, when there will be enough doses for all of them, and how to identify and contact people with high-risk health conditions, said James Garrow, a spokesperson for the city health department.

» READ MORE: COVID-19 is making ER physician burnout worse than ever. Jefferson, UArts researchers seek ways to help.

Meanwhile, shots are going into the arms of the region’s hospital workers. More than 18,000 Penn Medicine faculty, staff, and other health-care workers have received their first dose and an additional 4,000 are scheduled to receive shots in the coming days, said Penn Medicine chief medical officer P.J. Brennan.

At Temple University, Reed said the hospital system will likely finish scheduling first doses for most of its 18,000 employees, affiliated physicians, and medical students by the end of the month. Meanwhile, he said, doctors are preparing to start inoculating older patients, with priority for those with serious illnesses.

When the time comes, those high-risk patients will likely be contacted by their doctors and given shots in their doctors’ offices, though Reed anticipated that most healthy patients over 75 will likely schedule their shots through a call center. As different groups of people qualify for immunization, they will likely be able to sign up for appointments in a doctor’s office or community vaccination site, Reed said.

And Temple is expecting to partner with churches and community centers to bring vaccination sites into Philadelphia’s neighborhoods once more doses are available, Reed said. Brennan of Penn Medicine also said hospitals may set up off-site community testing facilities.

“In the end,” he said, “we’re ready as soon as government says we should do it.”

As Pennsylvania’s restrictions on indoor dining, gyms, and other businesses were lifted Monday, officials said they would be watching the case numbers in the coming two weeks to determine whether holiday travel and gatherings led to a spike.

Pennsylvania reported 4,579 newly confirmed cases on Sunday and 3,226 on Monday. The numbers were “abnormally low,” Levine said, because of maintenance on the state reporting system over the weekend.

On Sunday, 56 deaths were reported, and an additional 66 were reported on Monday. Levine said the death numbers were likely low because reporting slowed during the holidays.

Philadelphia, which won’t allow indoor dining until Jan. 15, announced 1,576 new cases, representing test results reported since Thursday, but Garrow also said the batch of test results received by the city was smaller than usual.

Though the three-week restrictions were lifted, the state remains under a stay-at-home advisory.

New Jersey reported 2,292 new cases and 38 deaths.

Persichilli, the health commissioner, said the Department of Health was in touch with hospitals and discussing preparations for a potential mid-January surge.

“If I’m anxious about anything, it’s the 14-day incubation period — postholiday, post-New Year’s Eve,” Persichilli said. “We will be as prepared as we can be.”

Staff writers Jason Laughlin, Tom Avril, Marie McCullough, Laura McCrystal, and Rob Tornoe contributed to this article.