Doctors in Bradford County keep pleading with patients: Consider getting the coronavirus vaccine. But lately, patients keep saying they want to wait.

The county, on the Pennsylvania-New York border, has seen COVID-19 cases and hospitalizations surge in recent days. While more than half of U.S. adults — and 43% of Pennsylvanians — have gotten at least one dose, barely a quarter of those in Bradford County have done so. And the state’s expansion last week of eligibility to all 16 and older didn’t bring a fresh rush to clinics.

“We are not filling appointments,” said Michael Scalzone, chief quality officer of Guthrie Clinic, which operates Robert Packer Hospital, the area’s largest facility, as well as smaller community hospitals in the county.

A similar April slowdown has shown itself 200 miles away in Philadelphia. Thousands of appointments have gone unfilled at the Convention Center over the last several days, and North Philadelphia’s federally run Esperanza clinic has also operated below capacity.

After months of high demand for hard-to-get vaccine appointments, the landscape has changed nearly overnight across the commonwealth. In both the state and city, officials expanded vaccine eligibility to all adults a few days ahead of schedule last week because providers reported difficulty filling appointments (New Jersey expanded eligibility Monday as scheduled). While it’s good news for shot-seeking residents, it hastens the next puzzle for officials and providers.

“The appointment availability does give us cause for concern,” acting Health Secretary Alison Beam said Friday, “because that’s indicative of the hesitancy, which really is the challenge to come.”

Meanwhile, a race is on between the vaccine and the virus variants, some experts say, and the need for immunity could become more urgent.

» READ MORE: COVID-19 still spreading through Philly region as more can get vaccine, but Pa. and N.J. see different trends

Overall, officials say demand has remained “very high” across the state, which is vaccinating people at a faster pace than most others. And plenty of providers are still booked up and busy. But instead of more supply and universal eligibility leading to a surge in demand, many providers are ditching wait lists and others have empty slots.

The developments signal a new phase of the rollout, said Philadelphia Health Commissioner Thomas Farley, who acknowledged that the city may spend months vaccinating a relatively small number of people per day. “Now we’re getting to the people who are less eager or more ambivalent, and it’s going to take longer to reach them,” he said Tuesday.

In the few weeks since eligibility expanded, providers with high demand have had a “natural flow of demand and supply,” as one said, while others with low demand are “a little bit surprised that … this slowdown has occurred” so soon, said Lebanon County administrator Jamie Wolgemuth. A level of vaccine hesitancy was expected, with many personal, philosophical, and political reasons for the reluctance, but some providers didn’t expect to be up against it so soon — or have it exacerbated by last week’s pause on the Johnson & Johnson vaccine.

With eligibility opening, many “kind of expected the surge we saw in January” in vaccine demand, said Eugene Curley, medical director of infection control for WellSpan Health, which serves Adams, Franklin, Lancaster, Lebanon and York Counties. “We just haven’t quite seen that yet.”

» READ MORE: Vaccine hesitancy is increasing among Gen Z. Targeted public health messaging can help, experts say.

Across the commonwealth, that puts the million-dollar question in the spotlight: Will enough Pennsylvanians get vaccinated to contain the virus, and how long will it take?

Between a fifth and a quarter of Americans do not plan to get vaccinated, according to two polls released last week by Quinnipiac and Monmouth Universities. Across Pennsylvania’s counties, between 11% and 19% of the population was predicted to be hesitant in an estimate by the federal government.

“We’re going to start hitting a wall here pretty soon where the people that you didn’t have to convince to have the vaccine are going to have the vaccine,” said Simon Haeder, a Pennsylvania State University public policy professor. That could happen before enough people are vaccinated to put the state “in a safe zone where you really don’t have to worry about spread.”

But, he said: “We still have a window of time to fix that.”

Mixed demand

While just weeks ago demand was high nearly everywhere, it now varies unpredictably from provider to provider -- cutting across rural, suburban, and urban communities.

While the University of Pittsburgh Medical Center’s chief medical officer, Donald Yealy, estimated in an interview last week that it would be “many weeks away, if not months’' before supply outweighed demand, Excela Health just 20 miles away has gone from administering 1,000 first doses a day a few weeks ago to just 300 last Tuesday.

That contrast is playing out in many places: Steady demand has been reported in Philadelphia’s suburbs and Allegheny County. Lehigh Valley Health Network sites last week set a record for the number of doses administered in a day, said Timothy Friel, chair of the department of medicine. At Wind Gap Community Pharmacy near Easton, people line up for shots before the store opens.

But Penn State Health’s Hershey clinic has 150 available appointments a day, with no-show rates reaching 10%, said senior vice president for ambulatory services Jeannette Gibbs, and 1,000 slots are open each day at the “Vaccinate Lancaster” site that it helps run. Geisinger’s clinics in rural Lewistown and Jersey Shore have seen decreased demand, too.

The Pfizer and Moderna vaccines must be used within a certain amount of time after being removed from freezers, adding another challenge to unpredictable patient volume. But shots aren’t being wasted: Only 0.11% of doses have been discarded, according to the Department of Health.

With so many different reasons for hesitancy, outreach must be tailored to what “your local demographics look like,” Haeder noted. Doctors will need to convince patients with unfounded health concerns, church leaders may be key in Black communities, where trust is lower due to historic racism in health care, and Republican leaders must endorse the vaccine to their constituents, who recent polling shows are much more likely than Democrats to say they plan to refuse the vaccine, experts said.

» READ MORE: As Americans scramble to get vaccinated, many rural, conservative Pennsylvanians feel no urgency

Some local efforts are already working. In rural areas of the northeast, demand has been “huge,” said Rural Health Corp. CEO Tiffany Tankalavage, in part because residents are more comfortable being vaccinated close to home by familiar providers.

“The trust factor is really there,” she said. “With our providers being vaccinated, they can say, ‘Hey, I had the vaccine; this was my experience; you should get one too.’”

It’s a similar story in Boyertown, Berks County, where 3,000 people get vaccinated at the high school gym every weekend.

“I would not miss that day for anything,” said pharmacist Ed Hudon, proprietor of the Medicine Shoppe in Boyertown, which runs the clinic on weekends. “People say I must be tired, and I am, but it is the most joyful experience to see the positivity and the possibility of getting through this.”'

‘An open question’

Supply problems dominated the first months of Pennsylvania’s vaccine rollout. Now the Department of Health is launching a $9 million messaging campaign promoting vaccination, working with community leaders, and boosting outreach to address hesitancy.

The Pennsylvania Department of Health hopes to get 80% of the population vaccinated, and Gov. Tom Wolf and Beam have encouraged more people to get immunized, assuring them that shots are safe and effective. Providers are also addressing patient questions and concerns, a mission more urgent since last week’s pause in the administration of the Johnson & Johnson vaccine over safety concerns.

“We recognize that it is critical for us to meet people where they are and we recognize that trusted messengers will be critical to shifting attitudes,” said Health Department spokesperson Maggi Barton.

» READ MORE: Scrambled plans, delays, and new fears accompany J&J COVID-19 vaccination pause across Philly region

In Philadelphia, Farley said he does not have a set percentage of the population that he would like to vaccinate, but would deem the effort a success if enough people are vaccinated that there are no deaths — or very few — even if the virus is still circulating.

”Whether we’ll get there, we don’t know,” he said. “How much we can reach those people who are not vaccinated yet is an open question.”

Lackawanna County tops the state at nearly 46% of all residents vaccinated, according to state data. The Philadelphia suburbs range from 36% in Bucks to nearly 45% in Chester County. City data put Philadelphia residents at 30% as of Tuesday.

In Bradford County, where 24% of people have been immunized, “it does not seem … that we’re looking at a population that will be 70 to 80% vaccinated,” Guthrie’s Scalzone said. “As much as I’d like to see that happen, I’m concerned it won’t.”

Added to the hesitancy mix: the possible fallout of last week’s J&J pause over reports of a rare clotting syndrome, which “hurt us even more,” said Gibbs of Penn State Health.

“What people forget to think through [is] what’s the relative risk of getting the disease vs. the complication of the vaccine?” said Yealy of UPMC. “I can tell you as a physician: The risks of getting the disease, even if you’re a healthy young person, are far higher than the risks of getting the vaccine.”

Given decreasing demand statewide, physicians say even a vaccination rate of 70% might not be achieved easily.

It “is going to be a bit of an uphill battle,” Lehigh Valley’s Friel said. “But not an impossible one.”

This story has been updated to clarify the data analysis of people vaccinated by county, which was calculated using the total population.

Staff writer Laura McCrystal contributed to this article.