Editor’s Note (10/4/19): This story is being republished today because the New York State Department of Health has announced that the state no longer has any active measles cases linked with the outbreak that started in October 2018.

As of mid-June, there have been more than 1,000 cases of measles across 28 U.S. states this year. The disease was declared eliminated in the U.S. in 2000 but has reappeared with a vengeance, mainly in isolated pockets of unvaccinated people. Those who choose not to immunize their families are not only placing themselves and their children at risk but also others who cannot be vaccinated either because they are too young or have medical issues.

There isn’t an iota of doubt that vaccines are a safe and effective way to prevent many diseases. All 50 states mandate that children entering school get immunized unless they have a medical-based exemption. Yet almost every state also offers religious exemptions, and more than a dozen offer personal belief/philosophical ones as well. California, Mississippi, West Virginia and, most recently, Maine have gotten rid of both sorts of waivers, and these states have some of the highest vaccination rates for measles and several other diseases. The others must follow suit. It’s imperative for protecting public health.

It doesn’t take many unvaccinated people to cause an outbreak. Measles is one of the first vaccine-preventable diseases to have reappeared because it is so contagious; the threshold for so-called herd immunity—resistance to a disease conferred by sufficient community levels of immunity or vaccination—is 93 to 95 percent. If vaccination levels fall below that threshold, an infected person can cause an outbreak.

Vaccine hesitancy is nothing new. People have questioned inoculations since Edward Jenner introduced the smallpox vaccine in 1796. Today vaccines are partly a victim of their own resounding success. People rarely if ever see once-common diseases such as measles or polio, so they don’t understand the potential danger. On top of that, relentless misinformation campaigns have touted such false claims as the idea that vaccines cause autism (numerous studies have shown they do not). The discredited researcher Andrew Wakefield introduced this idea in a now refuted study, and celebrities such as Jenny McCarthy and Robert F. Kennedy, Jr., have given it credence. And the Internet and social media have made it easier than ever for vaccine deniers to find like-minded networks of people to confirm their false beliefs.

Most major faith groups in the U.S. do not prohibit vaccination, and many religious leaders actually encourage it. Yet many people take advantage of these exemptions anyway, which can lead to outbreaks, especially in very insular communities. A large number of the recent measles cases have occurred in ultra-Orthodox Jewish communities in the neighborhood of Williamsburg in Brooklyn and in Rockland County in New York State. In spite of the outbreak, an antivaccine symposium held in the latter drew hundreds of attendees. (It’s not just the Jewish community: the majority of New York City schools with relatively low rates of students vaccinated against measles were Muslim or Christian academies or alternative-learning institutions.)

Many of the people who choose not to vaccinate believe that the government should not be able to force them to put medicine into their or their children’s body. They frame the choice as a personal right, but they are not taking into account the right of their children or others to be free from disease. When it comes to balancing the two, we need to consider the needs of the herd over the individual.

Some experts argue we should just make it more difficult to obtain religious and philosophical exemptions. But this strategy runs the risk of continuing to legitimize parents’ decision not to vaccinate their kids. Unless such exemptions are removed completely, there will always be people who will use them. Eliminating exemptions for only some vaccines, as the Washington State Senate did in the case of philosophical exemptions for the MMR (measles, mumps and rubella) vaccine, is also shortsighted, because it sends the message that some immunizations are less important than others. The only surefire solution is to eliminate nonmedical exemptions to all recommended vaccines.

Undervaccination is also part of the problem. Many kids do not receive all their vaccines on schedule because their parents forget to bring them in or simply feel they don’t have the time. Health care providers should strongly recommend that children get vaccinated—not just present it to parents as an option. Having schools and daycare centers send out reminders to parents has also been shown to be effective.

Health care access may also pose an issue for children from some households, but that has become less of a problem in recent years, thanks to programs such as the U.S. Centers for Disease Control and Prevention’s Vaccines for Children, which gives free immunizations to those who are unable to pay for them.

People who cannot be vaccinated for medical reasons—such as those with life-threatening allergies or compromised immune systems—should remain exempt. But there is no legitimate argument against vaccination for the vast majority of healthy people, and there are many powerful arguments in favor of it. We cannot continue to let a minority of people place the lives of their children and others at risk by allowing them to obtain nonmedical exemptions. It’s not a matter of freedom; it’s a matter of public safety.