NEW YORK - It's late on a Tuesday night during the worst measles outbreak in decades, and doctors, nurses and other health-care providers are gathered at a medical center to learn better ways of talking to parents who are reluctant to vaccinate their children.

Blima Marcus, an oncology nurse, leads the two-hour session on how to do a better job listening to and responding to parents' questions - and, in the process, cultivating their trust. The key, she says, is hearing people's questions about the science behind vaccines, and addressing those directly.

To debunk the false claim that childhood illnesses strengthen the immune system, for instance, she said doctors can explain that the immune system is not a muscle that gets stronger with exercise. "It's not a great idea to deliberately expose your children to an illness any more than you would break their leg bone because you think it would grow back stronger," she told the group at the Ezra Medical Center in Brooklyn's Borough Park neighborhood.

Marcus, part of the Orthodox Jewish community in Brooklyn, helped form a volunteer group of health-care professionals this year to confront vaccine hesitancy and misinformation that officials blame for the measles outbreak - now in its 10th month - that is predominantly sickening Orthodox Jews in Brooklyn. Her group, the Vaccine Task Force, has written and distributed thousands of booklets to parents to counter fears and myths spread by anti-vaccination groups that have targeted the community.

Now, she and other nurses are tutoring the doctors themselves about how to respond respectfully and effectively to such concerns.

Health officials in New York and across the country are increasingly trying new strategies to spread accurate information about vaccines. They are relying more on community groups instead of government agencies, in an acknowledgment of a broad distrust of science and government, particularly in culturally isolated communities.

"We think if we just speak louder, people will just accept that," said Jeremy Farrar, director of the Wellcome Trust, a global health foundation based in London. "We need to make a case for science and understand why people question it."

Another recently formed group, the Jewish Orthodox Women's Medical Association, runs a confidential hotline that families can call to request private, in-home vaccinations, so their children can be protected from measles without risking disapproval from anti-vaccine activists.

In Portland, Oregon, where anti-vaccination sentiment is strong, Boost Oregon, a nonprofit, holds free workshops about vaccination for new and expecting parents. The workshops, taught by medical professionals, often run two hours or longer to allow parents to get all their questions answered. The organization also provides seminars to doctors, nurses, midwives, naturopaths and others on how to address patients' misunderstandings about vaccinations.

A recent global study of public attitudes about health and science by Wellcome Trust, conducted by Gallup World Poll, found that more than 8 in 10 people trust medical workers for health advice, and that the most trusted source of health advice is a doctor or nurse.

Nurses, in particular, can play a critical role.

"We're the first and last person a patient sees before they make a final decision," said Melody Butler, an infection specialist at Good Samaritan Hospital on Long Island who also heads a group called Nurses Who Vaccinate.

In New York, the inability to fully engage the Orthodox community on vaccination has "been really a lesson for us," New York City Health Commissioner Oxiris Barbot said at a recent discussion at NYU Langone's Tisch Hospital. Given the community's distrust of government, Jewish organizations are critical for providing information. "Public health doesn't always have to be the messenger," Barbot said.

At the recent session in Brooklyn, Marcus addressed the most common pieces of misinformation spread by anti-vaccination activists. Her presentation was succinct and packed with practical tips: Here's how doctors can show parents how to find reputable studies online. Here are responses to 13 common concerns about vaccines, from ingredients to side effects.

If patients are worried about vaccine ingredients, Marcus told the providers as they snacked on pizza and potato chips, explain that aluminum hydroxide, for example, is used to improve the immune response and make the vaccine more effective. Half the aluminum in a vaccine clears the body within 15 minutes, and 99% is excreted within two days, she said. Studies have found no correlation between infants who received aluminum-containing vaccines and cognitive development, she said.

What's more, she said, certain foods contain natural chemicals that are toxic to humans. Pears have more formaldehyde than vaccines, she said. But the chemicals are present in very small amounts, far below the harmful dose.

To rebut anti-vaccination misinformation linking a rise in chronic childhood illnesses to the increase in required childhood immunizations, doctors can explain that correlation is not causation. She pulled up a slide showing a decrease in Maine's divorce rate that happened to correspond with a drop in the per capita consumption of margarine. That doesn't mean there's a relationship between the two, she said, prompting chuckles.

She also provided handouts listing dozens of evidence-based studies that backed up her points.

"Patients are constantly told vaccines are safe, but no one has ever shown them the studies," she explained in an interview after the meeting. "Well, here they are, with references, outcomes, population sizes."

The measles outbreak has slowed in New York and across the country, but officials are worried about the potential for continued spread at summer camps, during travel to Europe and other regions experiencing measles outbreaks, and with the start of school in the fall.

New York eliminated the religious exemption to vaccine requirements for schoolchildren last month, and Marcus said she expects to get requests to hold more workshops for parents and health-care providers. She is hopeful that parents will more readily accept information. "Now they know they need to vaccinate; they're coming to really learn and not to challenge you," she said.

Pediatrician Jeffrey Teitelbaum, director of the medical center, was among those who attended the session. The center receives about 70,000 visits a year; Teitelbaum, 55, has about 2,000 patients. Over the years, he has faced parents who were reluctant to vaccinate their children.

But this time, he has noticed a big difference.

In years past, he said, parents were sheepish when they explained they wanted to delay or shun the shots. Now, they're defiant.

"They're challenging the trust of the government and the medical establishment. It's much more challenging to overcome," he said in an interview. On top of that, providers are often being asked to provide the evidence for their recommendations to patients.

Alisa Minkin, a Long Island pediatrician who attended the meeting, said it's virtually impossible for physicians to have at their fingertips all the details of "anti-vax lore" and be able to refute points with patients during a 15-minute visit.

Teitelbaum said the tips, such as the one about chemicals in pears, have proved handy and drawn chuckles from patients. Most patients get vaccinated, he said, but for the very few who "aren't going to take my word for it," he said, it's useful to have other ways of communicating information.

At a time when many patients choose doctors based on insurance coverage, there often isn't enough time to establish a deep doctor-patient relationship, Teitelbaum said. The talking points from Marcus's group can help doctors maintain a relationship with patients. The hope, he said, is to build on that "so in the future, they have the ability to vaccinate."