Long Beach is experiencing a trip back in time - an outbreak of the mumps, which many considered a childhood rite of passage until an effective vaccine was developed in 1967.

Health officials have confirmed at least 36 cases of the highly contagious virus, contained in a small geographic area. Officials are urging everyone in the area to wash their hands more often, and - in a very 21st-century twist - to get the measles, mumps and rubella (MMR) vaccine if they haven't already.

"We're trying to prevent this from getting larger," Lawrence Eisenstein, Nassau County's health commissioner, told ABC News.

In the past, health officials could be relatively certain that Americans had received the MMR vaccine between 12 and 15 months old, and then been given a booster between ages 4 and 6.

It's true that the vaccine is not 100 percent effective against the mumps - there are four or five breakouts in New York every year, according to Dr. Bruce Farber at North Shore University Hospital in Manhasset. And health officials speculate there may be a new strain of mumps going around.

But the call for immunization wasn't something we would have witnessed 15 or 20 years ago. The MMR vaccine has acquired a bad reputation, and more parents are refusing or delaying shots on behalf of their infants. Arkansas health officials have asked students without the vaccine to stay home in response to a school outbreak. And five dozen cases threatened Harvard's graduation ceremony in May.

In a survey published Monday, the American Academy of Pediatrics said that 87 percent of its members in 2013 had encountered parents who refused vaccines, up from 75 percent of pediatricians in 2006.

I used to support opting out of vaccinations. The refuseniks raised some valid questions about how many and which immunizations were necessary.

For example, if a person contracts chickenpox without having been vaccinated, he or she might be sick for a week. With the vaccine, a child might be ill for five or six days. Is it worth a shot to be well two days earlier? Hard to say for sure - but it does seem to benefit vaccine manufacturers in the wallet.

For a long while, people suspected that the MMR vaccine caused autism - a connection that has now been debunked by many studies but is still supported by celebrities like Jim Carrey and Jenny McCarthy.

It's reasonable to respect people who are willing to do the research, to listen to the other side of a story - people who don't necessarily take someone else's word for what's true, even if it's the word of a physician or the Centers for Disease Control and Prevention.

But anti-vaxxers have taken skepticism too far. Confronted with the science, they choose to believe the less supportable theories. Science isn't a certain discipline; it's the best hypothesis we have at any given time, and it can change. But that doesn't make it evil or corrupt.

Somehow, we've arrived at a point where questioning institutions, without any benefit of evidence, is admired. The suspicious person, the contrarian, takes on a veneer of knowing more. You see glimmers of this in Long Island's constant NIMBY operations and in the Common Core opt-out movement.

When you can find support for just about any wacko theory on the internet, the stance of the contrarian can be dangerous.

What made me drop my support for parents' choice over vaccinations was learning about herd immunity. The refusal doesn't just affect the individual but puts others in harm's way. In 2014, a single unvaccinated child with measles at Disneyland led to 146 people sick. People who refuse vaccination are free-riding on the large majority of people who do vaccinate.

Sometimes, it's simply not adequate to decide what's best for oneself. Sometimes, we have to think of our neighbors.

First published in Newsday. Anne Michaud is the Interactive Opinion Editor for Newsday.