"My mom is a very stereotypical all-natural person, and she doesn't want chemicals being put into my body," says "Ester," a 16-year-old sophomore who spoke to me from a hiding place in her bedroom closet. "I used to share all those beliefs. But with things like vaccines, you have to look at the evidence—and when I looked at the evidence, I changed my mind. I want to get vaccinated."

Ester, who asked that her real name not be used, isn't alone. In recent months, dozens of teenagers have come forward online and in the media to demand the right to get vaccinated without their parents' permission. Perhaps ironically, they use the same rhetorical appeals to self-ownership as their parents, and they raise interesting challenges to a movement that claims to champion choice. As Stacy Methvin, an activist with Texans for Vaccine Choice, a group that defends people's right not to vaccinate their children, puts it: "We, as humans, have the right to choose what to do with our bodies."

But what happens when a teenager wants to make a different choice?

In 2000, the Centers for Disease Control and Prevention (CDC) declared a triumph: Endemic measles, which had once claimed an estimated 400–500 lives per year and was responsible for thousands more hospitalizations, had been eliminated in the United States. But the celebration was short-lived. In the time since, measles outbreaks in the U.S. have spiked. In 2018, there were 349 reported cases, and the trend seemed poised to continue into this year. Washington state officials declared a public health emergency in January 2019 as the disease began to spread near Oregon, with 74 confirmed cases as of March 22. According to the CDC, 90 percent of reported cases in the United States are linked to people who are unvaccinated or whose vaccination status is unknown.

"Anti-vaxxers" (or "vaccine choice activists," as some prefer to be called), have been around for as long as vaccines themselves. But opposition to vaccines gained momentum in the United States in the '90s, after British doctor Andrew Wakefield released a fraudulent research paper linking the measles, mumps, and rubella (MMR) vaccine to autism. That paper has since been widely debunked, and Wakefield was stripped of his medical license. Nevertheless, the percentage of unvaccinated children in the United States, while still a minority of the overall population, has quadrupled since 2001.

Although hundreds of medical studies have found that vaccines are safe and effective, the anti-vaccination movement is growing worldwide. Its rhetoric often appeals to one of the most cherished human rights: self-ownership and the freedom to exercise choice about what happens to our bodies. This wave of unvaccinated children is entering adolescence in a different era than the one in which their parents made decisions for them as infants—even Disneyland has been the epicenter of an outbreak—and they've started to ask human rights questions of their own: At what point, and in what contexts, should teenagers have the right to make medical decisions for themselves?

There are no federal laws regarding a minor's ability to consent to vaccinations, and state regulations vary. In most places, parental consent remains the legal requirement for adolescent medical care, regardless of the age or maturity of the patient. That means most unvaccinated kids have to wait until they turn 18 to overrule anti-vaxxer parents—but there are exceptions.

In Oregon, for example, anyone 15 or over can consent to immunizations without parental permission. A Montana statute gives consent authority to any teenager who has graduated from high school. In Alaska, minors can give consent for medical care if a parent is unable or "unwilling" to do so. In other states, including Idaho, Illinois, Kansas, Maine, Massachusetts, Illinois, Nevada, Tennessee, Washington, and West Virginia, a relatively new legal concept called the "mature minor doctrine" allows unemancipated minors to petition a court for the right to make medical decisions for themselves, although the specifics of these laws vary and sometimes include requirements regarding age or parental availability. Most states with mature minor doctrines have parallel legislation that absolves parents of any obligation to pay for medical care that occurs without their consent, but that's not an issue in this case: The federally funded Vaccines for Children program provides free immunizations to anyone up to age 19 who would be otherwise unable to pay.

Yet in most states, options for judicial bypass are grim.

"To override parents, you have to meet certain conditions: There has to be a proven intervention that can fix a problem, and there has to be an imminent threat to the health of the child," says Arthur Caplan, the head of the Division of Medical Ethics at the New York University School of Medicine and author of Vaccination Ethics and Policy (MIT Press). "It is very unlikely that, legally, any judge would [authorize] a vaccine just as a preventative, since it [probably wouldn't] meet the standard of preventing imminent death and disability."

Sexual health is a notable exception. While 37 states require parental notification or consent in a minor's decision to end a pregnancy, according to the Guttmacher Institute, the remaining 13 states don't require any parental involvement at all. In other words, it's easier for a teenager to get an abortion than to get the measles vaccine without permission.

On top of that, all 50 states explicitly allow minors to consent to treatment for a sexually transmitted infection (STI)—and while 18 states allow physicians to notify a minor's parents that he or she is seeking STI services, no state requires it. A few states, such as California, even include the word prevention in the laws allowing minors to consent to STI care, so a vaccine for something that's sexually transmissible—human papillomavirus (HPV) or hepatitis B, for example—would be accessible to minors in those places. Adolescent access to mental health and substance abuse care is similarly expansive.

Teenagers who have children of their own represent another legal paradox: In all states, teen parents, like other parents, are presumed to be the appropriate decision makers for their kids, even when they cannot legally direct their own medical care. In other words, it's possible that a teen parent could get vaccines for her children—but not for herself.

The debate between vaccine advocates and vaccine skeptics is heated and often includes violent rhetoric—so much so, in fact, that multiple experts on adolescent health law refused to discuss the issue on the record, even to describe existing policy. Vaccines have been compared to rape, the Oklahoma City bombing, communism, and even the Holocaust. Memes circulate online in which anti-vaxxer parents use images of guns to illustrate how far they'd be willing to go to stop their kids from getting immunized. "Want to forcibly vaccinate my child?" reads one such image, in which a woman points a pistol directly at the camera. "Let's trade shot for shot. I go first." So when teenagers attempt to defy anti-vaxxer parents, emotions can run deep.

When Ethan Lindenberger, 18, a high school senior in Ohio, decided to get immunized despite his parents' objections, his mother told the science magazine Undark that the decision was "a slap in the face….It felt like him spitting on me." Another teenager posted on Reddit that his mom would be "livid" if he managed to get vaccines without her permission. It'd be easy to write off situations like this as just the newest display of teenage rebellion—one Twitter user joked that while kids in past decades snuck out of the house to get drunk or high, today's teens sneak out to get vaccinated—but most children who reject anti-vaxxer logic are, in fact, motivated by respect for authority. When Lindenberger showed his mom an article from the CDC explaining that vaccines don't cause autism, she dismissed it with "that's what they want you to think." But he wanted to defer to the experts.

"I was just blown away that, you know, the largest health organization in the entire world would be written off with a kind of conspiracy theory-like statement like that," Lindenberger told NPR.

The debate about whether adolescents can choose vaccines is contentious, but it's not unique in that respect. Teen abortion is a lightning rod, of course, but recent years have raised other controversial questions as well. As the number of children and adolescents seeking support for gender dysphoria has soared, for example, debates have erupted about whether parental permission should be required to access gender-affirming medical care, such as a puberty blockers or hormone replacement therapy. Even questions about a teenager's capacity to reject lifesaving interventions have emerged: In 2007, a Washington superior court judge ruled that 14-year-old Dennis Lindberg, a Jehovah's Witness and a leukemia patient, was mature enough to reject a blood transfusion on religious grounds, despite the objections of his biological parents. "I don't believe Dennis' decision is the result of any coercion," the judge said at a hearing. "He is mature and understands the consequences of his decision." A few hours later, the eighth-grader died.

These conversations often refer to a 1982 study that considered scenarios including diabetes, depression, and epilepsy and found that 14-year-olds "demonstrate a level of competency equivalent to that of adults" when making medical decisions. "The ages of 18 or 21 as the 'cutoffs' below which individuals are presumed to be incompetent to make determinations about their own welfare do not reflect the psychological capacities of most adolescents," the study concluded. In 2011, a Canadian study found similar results: When researchers presented adolescents and adults with information about stimulant treatment for attention deficit disorder, they found that the teens were just as qualified to understand the information and give informed consent as their parents.

In 2016, the American Academy of Pediatrics updated its policy statement on informed consent in pediatric practice. In it, the group acknowledges the critical (and unavoidable) role of parents as surrogate decision makers in early childhood but also points out that the limits of parental authority should be "constrained by respect for the child." It concludes: "Physicians should recognize that some pediatric patients, especially older adolescents and those with medical experience because of chronic illness, may possess adequate capacity, cognitive ability, and judgment to engage effectively in the informed consent or refusal process for proposed goals of care."

Many doctors, such as NYU's Caplan, emphasize that the best solution for kids who want vaccines might also be the simplest: talking to their parents. Some adults are hesitant, "but they're not always dyed-in-the-wool opponents," he says. "I think what we should tell kids who want to do this is: Get in front of the doctor and bring your parents in. You may be able to persuade them."

Stacy Methvin, the activist with Texans for Vaccine Choice, agrees. If her teenage son wanted to get an immunization, Methvin says she'd feel "heartbroken"—but she'd still talk to him about it.

"I'd explain why I have my beliefs, but I'd listen to his opinions too," Methvin says. "If he had done his research and felt very strongly, I'd probably allow him to get [vaccinated]. It would be a difficult situation, but kids have their own opinions. They can be smart and very thoughtful."

For some teenagers, though, that's just not an option.

"My parents are authoritative figures, and their word is law," says 16-year-old Ester. "I tried to talk to my mother, but she wasn't too keen on that. It's weird—she vaccinates our pets but not her children."

Given the lack of other options, Ester admits she'll have to wait until she turns 18. But as outbreaks become more common—and as teenagers escape their closets and start exploring their options—there's always the chance that a few physicians could go rogue.

"Ethically, I think there are older kids—15, 16, 17—who can make a decision about a topic like vaccination," says Caplan. "It raises a question for the doctor: Do they just want to do it without the parents' knowledge and take the risk? Sometimes I think you could make the case that, yeah, that might be the moral thing to do."