DENVER — Disneyland is supposed to be the "Happiest Place on Earth," not the place where you contract a highly contagious, once-eradicated disease.

Unfortunately, that is what happened at Disneyland in California, starting back in December. The measles virus, likely carried by a tourist from a foreign country, started a chain of infections that has now reached at least 87 people in seven states and Mexico. The outbreak has also resurfaced arguments surrounding the vaccination of children.

At least 73 of the reported cases are in California, a state with large pockets of people opposed to vaccination. Some places in southern California reach unvaccinated rates of double digits, sometimes tripling the state and national averages, which are around 3% and 5%, respectively.

Dr. Paul Cieslak is a Catholic parent of six who has overseen the Acute and Communicable Disease Prevention section in the Public Health Division of the Oregon Department of Human Services (DHS) since 1995. He is also a member of the Catholic Medical Association, an organization committed to upholding the teachings of the Catholic Church while advancing the profession of medicine.

According to Cieslak, opposition to vaccines largely comes from misinformation regarding side effects.

“It is true that, occasionally, you can get a nasty side effect from a vaccine, as from any medicine,” he told CNA. “That said, the vaccines are very safe: Tens or hundreds of millions of doses of this thing have been given with very little problem.”

Others who oppose vaccines fall into the category of religious or conscientious objectors. Many who oppose vaccines on religious grounds do so because the cell lines of some vaccines were developed from cells of aborted fetuses.

Dr. Marie Hilliard is a canon lawyer and the director of bioethics and public policy at the National Catholic Bioethics Center (NCBC), a nonprofit research and educational institute committed to applying the moral teachings of the Catholic Church to ethical issues arising in health care and the life sciences.

The NCBC, along with the Pontifical Academy for Life, have studied the moral issues surrounding vaccines and have determined that it is morally licit, and even morally responsible, for Catholics to use even those vaccines developed from aborted fetus cells.

“There’s a whole formula for examining these dilemmas in terms of what we call cooperation in evil, and there are certain things that are always wrong, and there are certain things that are tolerable,” Hilliard told CNA.

The Pontifical Academy for Life determined that the good of public health outweighs the distanced cooperation in the evil of the abortions performed in the 1960s from which the cell lines were developed. No new abortions have been performed to maintain these vaccines, and no cells from the victims of the abortions are contained in the vaccines.

Currently, the vaccine lines for rubella, chicken pox and hepatitis A are the remaining vaccines that have been developed from aborted fetal cells and for which there is no alternative available.

“One is morally free to use the vaccine regardless of its historical association with abortion,” reads a document from the NCBC based on the findings from the Pontifical Academy for Life. “The reason is that the risk to public health, if one chooses not to vaccinate, outweighs the legitimate concern about the origins of the vaccine. This is especially important for parents, who have a moral obligation to protect the life and health of their children and those around them.”

Those particularly susceptible to disease who can benefit from “herd immunity” (when the majority of a population is vaccinated) include children too young to be fully vaccinated, pregnant women and those with suppressed immunity, such as cancer patients.

The document goes on to say that Catholics should express their opposition to vaccines developed from aborted cells and that there is an obligation to use alternative vaccines, should they exist.

Cieslak said he has vaccinated his children and encourages his patients to do so as well.

“As a parent, I don’t want my kids to get sick. I want them to feel confident when they go into school or crowds or other settings, that they don’t have to fear whatever disease,” he said. “As a doctor and especially as a public-health guy, I like to see the disease rates go down; I like to see the population healthier; I like to see less money being spent on treating diseases that are preventable.”

Still, Cieslak believes that people should be allowed the freedom to refuse vaccines if they yet cannot reconcile them with their consciences.

“I think we are not cooperating in the evil of abortion by vaccinating our kids, because we had nothing to do with the original abortions; that’s a done deed,” he said. “But, still, I know parental consciences are bothered by this, and I think some rightfully so, and so I think we need to respect that.”

Barbara Loe Fischer, co-founder and president of the National Vaccine Information Center, believes all parents should have the right to informed consent and should be allowed to determine which vaccines, if any, are right for their children.

“Informed consent means that you have the right to be fully informed about the benefits and the risks of medical intervention and be able to exercise voluntary decision-making; you’re able to make a voluntary decision without being coerced or harassed or punished for the decision you make,” Fisher told CNA.

“It’s an ethical principal, it’s a human right, and that means it should apply to vaccines as well.”

Fischer said she is concerned about the “blame and shame” being poured out on the unvaccinated in the wake of the recent measles outbreak and encourages parents to read the product-manufacturer inserts of vaccines as well as medical literature and information available on sites such as the Centers for Disease Control’s website.

“I think that when people are judging the quality of information, they only need to look at it and ask: Are the statements backed up?” she said. “And if they’re backed up with good resources, then they can take that more seriously.”

While the new measles cases are cause for concern, the outbreak isn’t nearly as bad as it could be, and that is thanks to vaccinations, Cieslak said.

“The fact that it doesn’t spread to everybody is a testimony to the fact that most of them [who were exposed] are immune, and most of them got that way through vaccinations,” he said. “And when we have seen transmission of multiple cases, it has been largely among unvaccinated people.”

“As a Catholic, I would argue that it’s a socially conscious thing to do,” Cieslak said. “It’s not only good for you, it’s good for your fellow man.”

Frequently asked questions about vaccines from a moral standpoint can be found on the National Catholic Bioethics Center website at NCBCenter.org/page.aspx?pid=1284.

The Pontifical Academy for Life’s statement on vaccines can be found at COGforLife.org/vaticanresponse.htm.