NEW YORK (NYTIMES) - "The Vaccine Safety Handbook" appears innocuous, a slick magazine for parents who want to raise healthy children. But tucked inside its 40 pages are false warnings that vaccines cause autism and contain cells from aborted human foetuses.
"It is our belief that there is no greater threat to public health than vaccines," the publication concludes, contradicting the scientific consensus that vaccines are generally safe and highly effective.
The handbook, created by a group called Parents Educating and Advocating for Children's Health, or Peach, is targeted at ultra-Orthodox Jews, whose expanding and insular communities are at the epicentre of one of the largest measles outbreaks in the United States in decades.
On Tuesday (April 9), New York City Mayor Bill de Blasio declared a public health emergency in parts of Brooklyn in an effort to contain the spread of measles in ultra-Orthodox neighbourhoods there.
He said unvaccinated individuals would be required to receive the measles vaccine - or be subjected to a fine - as the city escalated its campaign to stem the outbreak.
Peach's handbook - with letters signed by rabbis and sections like "Halachic Points of Interest" - has become one of the main vehicles for misinformation among ultra-Orthodox groups, including Hasidim. Its message is being shared on hotlines and in group text messages.
"Vaccines contain monkey, rat and pig DNA as well as cow-serum blood, all of which are forbidden for consumption according to kosher dietary law," Mr Moishe Kahan, a contributing editor for Peach magazine, said in an e-mail.
Vaccines are often grown in a broth of animal cells, but the final product is highly purified. Most prominent ultra-Orthodox rabbis agree that vaccines are kosher, and urge observant Jews to be immunised.
Still, from enclaves in suburban Rockland county to the bustling streets of Brooklyn's Borough Park neighbourhood, flyers tell the Hasidim to be sceptical of immunisations.
On a recent Sunday evening, a four-hour conference call promoted to ultra-Orthodox families - with call-in numbers for a variety of countries - offered advice from speakers who were presented as experts in vaccine science.
The anti-vaccine movement goes beyond the confines of the ultra-Orthodox community. There are thriving and growing pockets of vaccine opponents across the country that span ideological boundaries: In Washington state, some liberal communities shun vaccinations while conservative populations in Texas also oppose them.
In New York's ultra-Orthodox community, the anti-vaccine movement has no clear public leader. Jewish leaders have said its message has spread through grassroots activism and has found a foothold largely because many Hasidim have limited access to the Internet or rigorous scientific research.
By some estimates, there are approximately 300,000 ultra-Orthodox Jews in New York; most live in Brooklyn's Williamsburg and Borough Park neighbourhoods and in Rockland county.
The majority of ultra-Orthodox Jews emphatically say they would never go against the advice of doctors, and health officials say most Hasidim are vaccinated. "I don't understand anyone that doesn't vaccinate," Mr Abe Kornbluh said as he stood at the front of Bleu, his restaurant on 13th Avenue in Borough Park.
But there have been dozens of sick children whose parents have hid their measles diagnoses from the public. And as public officials have scrambled to curtail the highly contagious disease, groups like Peach, whose members are mostly anonymous and are supported by national anti-vaccine organisations, have only intensified their messaging.
Many of the vaccine sceptics cloak their rhetoric with scientific language, as did the speakers on the recent conference call.
The call, which was advertised on flyers and accessible to anyone with the call-in number, told participants its goal was to "create an intelligent discussion about what we are putting into our children".
It featured speakers who were rabbis, doctors and lawyers, all of whom touted postgraduate degrees as they downplayed the dangers of measles and questioned the efficacy of vaccines.
A Hasidic mother who lives in Rockland county and participated in the call told The New York Times that none of her three children were vaccinated, and all of them recently had measles.
The woman, who spoke on the condition of anonymity for fear of retribution, said that she did not report the cases to doctors and that the children recovered in a matter of days.
"The body is not a machine," she said. "The body is something that reacts to toxins in certain ways. I've heard firsthand of cases of SIDS after children getting a vaccine," she added, referring to sudden infant death syndrome. Many studies have concluded that vaccines do not cause SIDS.
The measles outbreak began in New York in October, after ultra-Orthodox Jews returned from Israel where they celebrated Sukkot, a Jewish harvest festival. They had prayed at the Western Wall, eaten in sukkahs and vacationed in the warm weather.
But Israel was in the midst of a months-long outbreak, and health officials have said that several unvaccinated children came home with the virus.
As doctors confirmed the first cases in New York, health officials and Jewish leaders rushed to stop the spread of the disease, which the US had declared eradicated in 2000.
Flyers that emphasised the importance of vaccinations were dispersed. Health experts organised meetings with Jewish pediatricians, and thousands of doses of the measles-mumps-rubella (MMR) vaccine were dispensed.
The majority of ultra-Orthodox rabbis said they, too, urged vaccination, citing religious scripture about protecting one's health and the health of others.
But all of that has not been enough to persuade vaccine sceptics.
Mr Yosef Rapaport, a Hasidic journalist in Borough Park who has written about the importance of vaccination, said parents who do not want to immunise their children will seek rabbinical counsel that aligns with their views.
"You make up your mind and then try to find the interpretation in the Talmud," he said. "You can always find some rabbi who will express doubt."
Dr Aaron Glatt, an infectious disease specialist who is also an ordained rabbi on Long Island, says he has explicitly pushed back on misinformation about the dangers of vaccines.
He has emphasised to his patients and congregants that measles is spread by the unvaccinated and can be deadly, especially for infants under six months old and people with compromised immune systems, who cannot get vaccines.
"Unfortunately, we are not immune to anti-vax people," Dr Glatt said. "They're found in every community, in every religion, and unfortunately, they're vocal."
Dr Yakov Kiffel, a paediatrician in Monsey in Rockland county, said that he has both vaccinated children and treated about a half-dozen patients with measles since the autumn. He said the majority of the sick were under six months old - the age at which a child can be given the first dose of the MMR vaccine - and members of families that said they vaccinate.
More than 400 measles cases have been confirmed in New York since October, and the majority of them have been among Hasidim.
In the past week, according to the Centres for Disease Control, there were 60 new cases reported in New York City. Nine new cases were confirmed in Rockland county, which last month took the extraordinary step of barring children who were not vaccinated against measles from public places. A judge ruled against the order last Friday, temporarily lifting the ban.
In the city, officials have prohibited unvaccinated children from attending schools in certain ZIP codes, predominantly in Williamsburg and Borough Park - an effort that has met mixed success.
Some Hasidim have said that longstanding tension between members of the ultra-Orthodox community and the government have made them wary of officials' efforts to contain the outbreak.
The past persecution of the Jewish people is still a factor, they said. And more recently, quarrels with secular leaders over a circumcision ritual that transmitted fatal herpes infections to infants and the government's oversight of ultra-Orthodox Jewish private schools known as yeshivas have only soured relations.
Some Hasidic parents also blame the absence of science education in yeshivas.
"The lack of a comprehensive secular education has raised a generation of some parents who do not appreciate modern science and do not have trust in the health system," said Mr Dov Bleich, a Hasidic father of two who lives in Monsey. He emphasised that most rabbis are supportive of vaccines.
"It's leaving them vulnerable to the anti-vaccine crusade."
Ms Blima Marcus, a nurse practitioner at Memorial Sloan Kettering Cancer Centre, is one of the many healthcare providers trying to counter that crusade.
Ms Marcus, the former president of the Orthodox Jewish Nurses Association, said her work began last autumn, after a relative included her in a text message with nearly 40 ultra-Orthodox mothers in Lakewood, New Jersey.
The majority of the women had not vaccinated their children, she said, but many began to reconsider that decision once she presented them with facts.
But Ms Marcus acknowledged that her efforts are too limited to have a significant impact on the outbreak.
Last Friday, rabbis met in Brooklyn to consider a proposal that would require all Hasidim to be vaccinated in order to attend synagogues and yeshivas. After the meeting, anti-vaccine organisers sent a robocall to Hasidic homes, urging people to persuade their rabbis not to support the measure.
Dr Paul Offit, director of the Vaccine Education Centre at the Children's Hospital of Philadelphia and co-inventor of a rotavirus vaccine, said people often do not understand the severity of diseases that have been eradicated by vaccines.
"Vaccines have been a victim of their own success," Dr Offit said.
"What upsets me is we haven't learnt from history," he added. "What history teaches us is that measles is a killer, and vaccines can eliminate this killer, but now because of our ignorance, we have to see children suffer."
Still, opponents of vaccination ardently maintain that diseases like measles are not dangerous.
"The adverse events from getting measles, they're very, very, very low," Dr Lawrence Palevsky, a paediatrician in New York, said on the recent conference call. There have been no reported deaths in New York state linked to the recent outbreak. But measles killed 110,000 people globally in 2017, according to the World Health Organisation.
In New York, people like Ms Shoshana Bernstein, a Hasidic mother in Monsey, worry about the potentially deadly consequences of listening to anti-vaccine proponents like Dr Palevsky.
"A basic Jewish tenet that every Jewish child is raised on, is love your friend like yourself," Ms Bernstein said. "This is woven into the very fabric of who we are, which is why the current situation is extremely frustrating because it is the complete opposite of our essence as Jewish people."