With 600 cases reported, the year 2014 holds the record for highest number of measles cases reported since the mid-1960s. This number is alarming, considering the measles vaccine was invented in 1971 and the disease was declared eliminated in 2000. The Centers for Disease Control and Prevention says the resurgence of the disease can be linked to unvaccinated children in communal spaces like Disneyland, where 102 of the cases reported in 2014originated. This assertion has sparked a political war of words, incurred attacks from people both for and against vaccines, and called into question exactly who in this country can afford to abstain from vaccinating their children.

The most common argument against the use of the measles vaccine is the claim that it causes autism. This erroneous notion is based on a 1998 study published in The Lancet, a weekly medical journal that claimed to have uncovered a connection between the vaccine and the spectrum disorder. However, the study was retracted and its head researcher, Andrew Wakefield, lost his medical license for fabricating data.

Nevertheless, people still subscribe to this idea. Notably, actress and model Jenny McCarthy has, for years, publicly insisted that toxins in vaccines cause autism. McCarthy has a 12-year-old son who was diagnosed with autism in 2005. In a 2007 interview with CNN she took a definitively anti-vaccine stance, stating that “there’s no way in hell” she would give any child of hers a measles vaccination, nor would she recommend vaccinating to new mothers or mothers-to-be.

In 2010 McCarthy responded to a Time article on correlations between vaccines and autism, saying, “Time magazine’s article on the autism debate reports that the experts are certain ‘vaccines don’t cause autism; they don’t injure children; they are a pillar of modern public health.’ I say, ‘That’s a lie and we’re sick of it.’”

Although sound bites like those above are ubiquitous, McCarthy still asserts that she is not anti-vaccine and merely calls for cleaner vaccine formulas and a parent’s right to choose for their children. Time’s Jeffrey Kluger has responded, “You are either floridly, loudly, uninformedly anti-vaccine or you are the most grievously misunderstood celebrity of the modern era.”

However contradictory her claims may appear, McCarthy and other vaccine skeptics have had influence on American parents. Liz Szabo of USA Today reported that up to 40 percent of parents avoid or delay vaccines for their children, “often due to myths about vaccines causing autism.” Szabo interviewed a Los Angeles mother, Jennifer Charness, who “hesitated” to vaccinate her two sons “partly because of books by actress Jenny McCarthy.”

“I was a young mom, reading all of her books, and she claimed her son had autism,” Charness told Szabo. “I thought ‘no, I’m not vaccinating.’ It was a big deal at the time.” Since the outbreak at Disneyland, Charness has vaccinated her children against measles.

Some parents want to raise their children in an organic, holistic, natural manner, and have the funds and resources to do so. Jack Healy and Michael Paulson of The New York Times wrote, “There is a particular subculture of largely wealthy and well-educated families, many living in palmy enclaves around Los Angeles and San Francisco, who are trying to carve out ‘all-natural’ lives for their children. Anti-vaccine parents whose children have endured bouts of whooping cough and chickenpox largely defended their choice to raise their children on natural foods, essential oils and no vaccinations.”

Healy and Paulson talked with Crystal McDonald, mother of a 16-year-old student at Palm Desert High School. Her daughter was sent home from school for two full weeks because she was unvaccinated for measles. According to the article, “McDonald and her husband, a chiropractor, decided to raise their four children without vaccines. She said they ate well and had never been to the doctor, and insisted that her daughter was healthier than many classmates.” When McDonald’s daughter was worried about missing AP classes due to her absence from school and suggested getting vaccinated, her parents refused.

“I said, ‘I’d rather you miss an entire semester than you get the shot,’” McDonald told The New York Times.

In wealthy Orange County, 50 to 60 percent of kindergarten or pre-k students at some schools are not vaccinated, and 20 to 40 percent of parents have asked for exemption from the vaccination requirement based on personal beliefs. Dr. Eric Ball, a practicing pediatrician in this area, told Healy and Paulson that he sometimes feels that he is “practicing in the 1950’s.”

In other cases, parents may choose not to vaccinate their children because of distrust of the government. Ohio State University researchers have found that people who trust the government to handle an epidemic are far more likely to vaccinate their children or themselves than those who are suspicious of politicians and governmental institutions.

Medical researchers and doctors are urging parents to put aside any ideological reasoning, acknowledge their privileged access to vaccines, and ultimately choose to vaccinate. At a February 4 news conference, Los Angeles County Department of Public Health Interim Health Officer Dr. Jeffrey Gunzenhauser strongly advised, on behalf of the department, unvaccinated people to get the measles vaccine. Kaiser Permanente has started sending automated messages to households with unvaccinated children.

Experts are concerned that the number of unvaccinated individuals—and subsequent reappearance of previously eradicated diseases all over the country—is damaging herd immunity, a term that refers to the decreased risk of contracting a disease of an entire population when the majority of that population is immunized. Enough people have foregone vaccinations that the required number of vaccinated people for efficacious herd immunity, a vaccination rate of 92 – 94 percent for measles, is no longer met. But those who choose not to vaccinate, a decision only available to those who can be vaccinated in the first place, are consequently putting others at risk. This poses a threat to those who cannot afford healthcare visits as well as those who cannot be vaccinated for medical reasons.

“Herd immunity is the only way to protect those with compromised immune systems who can’t take the vaccine,” Stephen Eubank, a disease transmission researcher at Virginia Tech, told Jo Craven McGinty of The Wall Street Journal. “That means pretty much everyone who can, should get vaccinated.” University of Michigan professor Gary Freed best summed up the end goal of this crisis and debate: “We need to work to make the dominant paradigm one of the protection of children through immunization—the socially accepted choice, the morally accepted choice, and the scientifically prudent choice.”

Icon by Emmanuel Mangatia via the Noun Project.