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“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 fetuses.

“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 epicenter of one of the largest measles outbreaks in the United States in decades.

On Tuesday, 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 neighborhoods 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,” Moishe Kahan, a contributing editor for Peach magazine, said in an email.