Health experts in New York City warn parents against participating in a dangerous trend that's currently gaining popularity: measles parties.

Measles parties are get-togethers where groups of parents expose their unvaccinated children to each other, so they can contract the disease on purpose. It's the latest blow to the city that has already been declared in a public health emergency due to the measles outbreak.

As CBS News notes, the faulty logic behind these parties is based on the way the immune system works: by building permanent immunity to the disease once the individuals become infected.

"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," NYC Department of Health Commissioner Dr. Oxiris Barbot says. "The vaccine has been proven safe and effective in preventing the spread of measles for decades and we have evidence."

Of course, in a measles infection, people don't instantly become immune. First, they get sick, which can be extremely dangerous and even deadly to the infected children.

What Happens When Children Are Exposed To Measles?

When children get the highly contagious virus, they experience high fever, cough, runny nose, watery red eyes, and Koplik spots inside the mouth. Within days, rash will begin to spread all over the body.

At the very least, measles cause patients considerable discomfort or conditions such as diarrhea and ear infections, but there are some potential complications that are much more serious.

According to the CDC, one out of 20 children with measles develop pneumonia, which is the most common cause of death of measles in children. One out of every 1,000 individuals with measles also gets encephalitis or the swelling of the brain, which can cause convulsions and leave children deaf or with an intellectual disability.

A rare disease that can also be caused by measles is subacute sclerosing panencephalitis, which is a fatal disease of the central nervous system that usually develops seven to 10 years after a measles infection.

As a whole, one or two out of every 1,000 children with measles die from the disease.

Vaccines Are Less Dangerous Than Getting The Disease

Scientists developed vaccines so that people can become immune without having to experience the stress and the dangers of getting sick with measles. Vaccines work by mimicking the infection, so the immune system develops the immunity necessary to fight against the virus in the future.

The MMR vaccine is safe and the best way to avoid getting sick with the disease, according to the CDC. A single dose of this vaccine is about 93 percent effective in preventing measles and two doses are about 97 percent effective.

"Because vaccines have been so effective at preventing previously widespread diseases, we tend to forget that measles and other childhood diseases can be very serious," Dr. Max Gomez, medical correspondent of CBS 2, says in CBS. "Why would you purposely expose your child to measles, causing them to feel awful, run a high fever (which can lead to seizures), risk expensive hospitalization and other potentially serious complications when a simple vaccine can prevent all that?"

He adds that an infected person could transmit the disease to another person whose immune system is compromised. In an immuno-compromised person, measles can quickly turn fatal.