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A day after federal agencies recommended a pause in the use of the Johnson & Johnson coronavirus vaccine while they investigate potential rare side effects, public health experts and providers in the Washington region on Wednesday said they are boosting education and transparency to combat potential worries among people about the shots.

Community leaders and those in charge of vaccinating vulnerable populations said that the pause does not appear to have immediately deterred people who want to be vaccinated or have upcoming vaccine appointments.

“My concern is the people who were already not planning to get the vaccine will latch on to this as further justification just for why they shouldn’t get it,” said Leana Wen, Baltimore’s former health commissioner and an emergency physician.

Federal officials recommended the nationwide pause in administering the Johnson & Johnson vaccine while they review a rare type of blood clot known as cerebral venous sinus thrombosis in conjunction with thrombocytopenia, or low blood platelets, which developed in six women — including a Virginia woman who died — who received that vaccine.

Public health officials say the pause is proof that the reporting system for adverse effects is working properly and that the Centers for Disease Control and Prevention and the Food and Drug Administration are taking even extremely rare side effects seriously.

The District, Maryland and Virginia stopped administering the Johnson & Johnson vaccine within hours of the federal recommendation, and clinics that were prepared to give that vaccine quickly switched to the two-dose Pfizer-BioNTech or Moderna versions.

For Unity Health Care, that meant starting its planned Johnson & Johnson clinic for construction workers at the Wharf in Southwest Washington a few hours late Tuesday morning while providers waited for frozen Moderna doses to thaw, said Jessica Boyd, Unity Health Care’s chief medical officer.

But the delay and news about the Johnson & Johnson vaccine didn’t prevent 350 people — more than anticipated before the pause was announced — from lining up there to receive their first shots in the two-shot regimen, she said.

Unity, which serves 100,000 low- and moderate-income people in District community health centers, homeless shelters and correctional facilities, has relied on its providers to educate and inform patients with whom they have long-standing relationships.

In addition to clinics and town halls, Boyd said even before the pause that one-on-one interactions have helped people feel more comfortable getting the shots although they might have had questions about how quickly the vaccines were developed and possible side effects.

“Particularly for the Black and Brown communities we serve, we still have the need to build the confidence in the vaccines that we have,” she said. “We take our role as trusted messengers very seriously.”

The one-dose Johnson & Johnson vaccine was particularly useful for people experiencing homelessness and transient individuals who may have trouble returning for a second dose, but Boyd said Unity had been using the Johnson & Johnson for only about a week before the pause.

Fewer than 400 of Unity’s clients received the Johnson & Johnson vaccine, in comparison with about 11,000 who received at least one dose of the Moderna vaccine, and only about 5 percent have not gotten second shots, she said.

Mark E. Whitlock Jr., the senior pastor at the Prince George’s County church Reid Temple AME, which partnered with Luminis Health Doctors Community Medical Center to host vaccine clinics for Prince George’s County residents, said one congregant contacted him Tuesday with concerns about the Johnson & Johnson pause.

“She and I had prayed, and I assured her that we had Pfizer and Moderna,” he said. “I am very concerned about the safety of the membership of Reid Temple. I am celebrating the fact that they did take it [the Johnson & Johnson vaccine] off the market.”

Vaccine supply and access — not hesitancy — remain his biggest concerns in Prince George’s, one of the communities hit hardest by coronavirus in the region.

The long-term impact of the pause will depend on what investigators discover and how they communicate their findings to the public, experts said.

“If we can’t confidently have the American public believe and trust in the safety and efficacy of vaccines, that could undermine the entire effort,” Danny Avula, Virginia’s vaccine coordinator, told reporters Tuesday.

But he said the six U.S. cases of blood clots associated with the Johnson & Johnson vaccine among the millions of doses administered are “exceedingly rare for a serious side effect.”

About 31 million people, or 10 percent of the U.S. population, have contracted the coronavirus, and 1 in 585 people in the United States have died of covid-19, he said.

“In relative terms, these are really low rates of incidence,” he said of the six cases. “All of this is like a big risk-benefit calculation,” he said.

Correction: An earlier version of this article incorrectly described a statistic about covid-19 deaths. One in 585 of people in the United States have died of covid-19, not 1 of every 585 people infected with the virus. The article has been amended.

Erin Cox contributed to this report.