BALTIMORE >> The new coronavirus booster shots have found a modest number of takers at one of this city’s few remaining public vaccination sites, with nine doses given on one recent day and 15 on another.

More than a month after the retooled shots were rolled out, only about 5% of Baltimore residents have received one, a figure that reflects the slow uptake nationally. In a city with stark health disparities, local officials see a reason to be worried.

“The fact that we’ve been getting it so often is making it uninteresting to people,” Rebecca Dineen, the city’s COVID-19 vaccine coordinator, said of the rounds of coronavirus shots.

The anemic turnout underscores yet another test of the Biden administration’s pandemic strategy as federal and local officials contend with dwindling public patience and diminishing funds for the virus response.

Only about 15 million doses of the new shots have been administered nationally since their introduction at the beginning of September, representing less than 1 in 10 people who are eligible, and there are signs that many Americans are unaware of or simply uninterested in them. In a Kaiser Family Foundation survey last month, half of adults said they had heard little or nothing about the shots.

Once defined by supply shortages and mass vaccination sites, the nation’s ever-expanding inoculation campaign has lately been characterized by apathy, with potentially serious health consequences for the most vulnerable Americans should another COVID-19 wave sweep the country this winter.

The tepid response to the shots, public health experts say, is more than just a marketing problem. Many Americans have recently had a coronavirus infection, drawing out the timeline for when they might seek another booster or causing them to skip one altogether. Others are wary of continual boosting or side effects that might keep them from going to school or work.

The turnout for the new shots, for which children as young as 5 became eligible this past week, could fall far short of the response to the initial booster campaign that the federal government undertook about a year ago, when administration officials say there was less fatigue around vaccination and the pandemic more broadly. About 110 million people received at least one dose of the original booster formulation before the new shots were authorized at the end of August.

Dr. Ashish Jha, the White House COVID-19 coordinator, said in an interview that the early turnout for the updated boosters amounted to a “good start” and that uptake was likely to steadily increase this fall. Many Americans, he said, were treating the new vaccines like flu shots, considering receiving one as the weather turned colder.

“We did not have an internal number in our heads, or at least I didn’t have one in mind, of what we were going to achieve,” Jha said. “My kind of mental model was that it would really start ramping up once we got into October.”

Administration officials made an expensive bet on the new campaign at a fraught moment in congressional funding negotiations, buying more than 170 million doses with billions in repurposed funds — enough to vaccinate most of the roughly 225 million Americans who have had an initial round of vaccination.

One senior official said the purchase was modeled on how the federal government typically buys flu vaccines, with enough doses to reach any American at tens of thousands of sites while limiting how many go to waste. About 80% of doses in recent weeks were given at retail pharmacies, Jha said, an increase from earlier COVID-19 vaccination campaigns.

Although many Americans still have substantial protection from past vaccinations and infections, federal officials have pointed to analyses that show the new boosters could still save thousands of lives. Vaccine experts say they expect the shots to deliver an initial burst of antibodies and a broadened immune response. The COVID-19 vaccines were redesigned to target omicron subvariants on the assumption that more current formulations would provide better and more durable protection.

Yet researchers are still working to determine how well the shots protect people and how long those defenses last. The data that federal regulators gathered from the manufacturers of the boosters, Pfizer-BioNTech and Moderna, is still preliminary, leaving experts to speculate about the additional benefits the new vaccines may offer, including their influence on transmission or longer-lasting symptoms of COVID-19.

Federal officials are not expected to have early data from Pfizer and Moderna on what kind of short-term antibody responses the new vaccines induced in trial participants until later this fall.

Health officials and providers already know whom they need to reach with the new shots, as Americans older than 75 have represented a majority of deaths from COVID-19 in recent months. About half of those vaccinated with the new boosters so far are seniors, Jha said.

White House officials say they have tried to publicize the new shots with federal ad campaigns, clinics at state and county fairs and partnerships with local leaders. The administration is targeting older Americans with outreach from the Centers for Medicare and Medicaid Services, while the White House is working with CVS and Walgreens to increase booster awareness, Jha said.

“When you walk into CVS, you see signs for the flu shot,” he said, adding, “We want to make sure that that is getting tied into their outreach on COVID-19 vaccines as well.”

Dr. Swati Gaur, medical director for two long-term care facilities in Georgia, said the challenge had shifted from getting a supply of vaccine doses to waging a piecemeal persuasion campaign to coax seniors into taking them.

In one recent encounter, she said, she spoke with a resident at one of her facilities who had grown tired of getting vaccinated against the virus after four shots and refused a fifth. She walked him through the potential benefits, and he agreed to get the shot.

Gaur said it was critical that employees at long-term-care facilities calling families and asking for consent to vaccinate knew how to have similar conversations.

Biden administration officials have offered sometimes competing ideas of the urgency of the booster campaign for younger, healthier people. Federal regulators scrambled to make the updated shots available ahead of schedule late in the summer, opting for that approach instead of offering second booster doses of the original vaccine formulation to all adults. With case counts lower, some top officials have recently offered a more relaxed timeline, turning to an October theme.

Jha encouraged Americans to get the new shots by Halloween so their immunity would be bolstered by Thanksgiving. “What we’ve been trying to do is give advice that simplifies it,” he said, adding, “The idea is that you don’t have to sort of think too hard about, are you eligible or are you not eligible.”

Some experts have warned that attempts to simplify messaging could backfire.

Dr. Walid Gellad, a drug-safety expert at the University of Pittsburgh, said efforts to reach all age groups had diluted attention to those who most need enhanced protection. When experts over the past year have questioned whether younger, healthier Americans need boosting, he said, “to those listening only halfheartedly, it will just sound like criticism of the booster, even though it was criticism of the booster in those age groups.”

With the new shots, more Americans are making guesswork out of the timing. Acting on expert advice, some of those who have recently had the virus are waiting three or more months to get boosted, while others are timing the shot for the holidays, travel or another uptick in cases.

Amanda First, 32, a lawyer in New York, said that after having a mild case of COVID-19 in July, she was not in a hurry to get the next vaccine dose. But she got one of the new boosters this month so that she would have more protection when spending time with family during the holidays.

“I’m cautiously optimistic it will provide me protection,” she said of the new shot. “But I wouldn’t be surprised if I’m reinfected.”

Munro Wood, a 33-year-old web developer near St. Louis, said he received his first booster in June but had grown tired of the idea of regular COVID-19 shots. He was still undecided on whether to get the new dose.

“Annual or even biannual boosters are uncomfortable enough that they don’t overcome the risk-reward threshold for me,” he said, adding, “If another, much worse variant comes out and starts spreading as rapidly as the initial omicron wave, I’ll probably perk up and pay more attention.”

Baltimore’s initial vaccine rollout included extensive advertising and grassroots work, and three-quarters of residents have now received at least one vaccine dose.

Dineen, the city’s COVID-19 vaccine coordinator, said city officials were still prioritizing getting first and second doses to vulnerable people in poorly vaccinated neighborhoods, where canvassers continue to go door-to-door with the shots.

Those at the city clinic one day this month were the vaccine-dedicated. “It’s something that needed to be done,” said Melvin Battle, a city employee, noting that “winter’s coming along.”

Paula Ladson-Gillis, another city employee, said she knew a dose of one of the new vaccines might not prevent her from getting COVID-19, but it would at least help to keep her from getting very ill.

“I know plenty of people are relaxed; I’m not one of them,” Ladson-Gillis said. “And that even says more to me why I want to get it, because too many people are not getting it.”

This article originally appeared in The New York Times.

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