New York City has declared a public health emergency in response to a measles outbreak in Brooklyn. The city has ordered mandatory measles-mumps-rubella (MMR) vaccinations for several zip codes in Brooklyn, and will issue fines to people not complying with the order.

There have been nearly 300 cases of measles in the city, particularly concentrated in Orthodox Jewish communities in Williamsburg in Brooklyn, Buzzfeed News reports. 

The leaders of the Orthodox Jewish community support people getting vaccinated, but uptake of the MMR vaccine has been low in the community itself, with resistance being "fueled by a small group of anti-vaxxers in these neighborhoods".

Anti-vaxxers have been specifically targeting the Orthodox Jewish community with misinformation. Peter Hotez, Professor of Pediatrics and Dean of the National School of Tropical Medicine at Texas's Baylor College of Medicine, told Buzzfeed News he's aware of anti-vaxxers phoning members of the community to spread the false information that vaccines cause autism, helping the disease to spread.

Trying to tackle this crisis, New York City has said that anyone within the zip codes 11205, 11206, 11221, and 11249 who have not received the MMR vaccine within 48 hours of the order "shall be vaccinated against measles unless such person can demonstrate immunity to the disease or document to the satisfaction of the Department that he or she should be medically exempt from this requirement".

Failure to comply with this new order could result in "forfeitures and penalties, including imprisonment".

Amid the crisis, the city has had to deal with another problem: People deliberately and voluntarily exposing their unvaccinated children to the (potentially deadly) disease.

"We are concerned about families having measles parties," New York City Health Commissioner Dr Oxiris Barbot said at a news conference, as reported by Fox News.

"There are many more individuals who are living with chronic diseases, who are surviving cancer, and so we don't want children or adults to be unnecessarily exposed to measles."

Measles parties, like chicken pox parties, involve bringing your child into contact with the disease in order to infect them. As you'd expect, this is a bad idea.

"CDC strongly recommends against hosting or participating in these events," the Centers for Disease Control and Prevention (CDC) write of a disease far less dangerous than measles. "Chickenpox can be serious and can lead to severe complications and death, even in healthy children."

It's far less safe than getting a vaccination, which the CDC deems safe.

"I know that parents may be afraid of getting their child vaccinated, but as a pediatrician. I know that getting vaccinated is far safer than getting measles. The vaccine has been proven safe and effective in preventing the spread of measles for decades and we have evidence," Barbot wrote on Twitter in a personal plea.

"Young children and people who have weakened immune systems cannot get vaccinated, so it’s crucial that everyone around them be vaccinated in order to shield them from the infection."

"Measles makes you sick," Barbot went on to say at the conference, Buzzfeed News reports. "Why would you let someone suffer that knowing there's a potential you could die?"