The Truth about Vaccines: A response to our critics


Do you remember Stephen of Bourbon? I wrote about him in this e-newsletter about a year ago. He was a 13th-century Dominican heresy hunter who traveled around France battling unorthodox religious ideas and superstitions. One day, near the city of Lyons when he was preaching against heresy and hearing confessions, Stephen “heard many women confess that they had carried their children to St. Guinefort.”


At first Stephen thought Saint Guinefort must be a local saint. He asked around and soon discovered Guinefort’s shrine — and the startling news that St. Guinefort was a dog.


Women came to the shrine hoping that St. Guinefort would drive evil spirits away from their infants. To help Guinefort expel demons the mothers engaged in rituals that would get them arrested today — including playing catch with their babies, tossing them between the trunks of two trees, and engaging in other activities that put the children at risk of drowning, of being eaten by wolves, or of being burned alive. As he related the dangerous things mothers did there, Stephen seemed a little surprised that any of the babies survived.


Stephen had the shrine destroyed and preached fiery sermons against it, but people kept coming. The reports of people venerating St. Guinefort the greyhound continued into the twentieth century. And in the end all Stephen could do was rail against “the diverse devilish delusions by which the Devil attacks the Christian people, drawing after him … innumerable souls of the stupid.”


As I said last time, those are harsh words. Nobody likes being called stupid, then or now. Perhaps a better word these days is “gullible.”


Even so, gullibility can be in the eye of the beholder. I doubt Stephen of Bourbon would have had his heresy and superstition radar beeping if St. Guinefort had been an orthodox monk whose shrine was accepted by the Church. The Church of his day saw no problem with visiting shrines for healing, or parents putting their children under the protection of a saint or praying to the saints to help keep their children from harm. And given the dismal state of what passed for medicine in the 13th century, praying to the local saint, even for the worst illnesses, usually did far less harm than putting your child in the hands of a doctor.


But since then something has changed: the birth of science — and its slow but progressive growth into adolescence today has changed our world.


I am a great admirer of science and what it has achieved. I admire the method of starting with anecdote or observation, stating a hypothesis, testing it, forming conclusions based on the test, and then testing it again and again as new questions arise. I admire it because it works. I admire it because it is self-correcting: Other scientists need to be able to replicate the test results. I admire it because it searches for evidence, establishes knowledge and facts, and then builds upon them.


Is science perfect? Of course not. Can it be misused by human beings? Yes, just as they do with religion, human beings can twist science for evil purposes. But science is the most reliable approach to the material world human beings have ever had, and it is one of the aspects of life that Catholics need not take on faith, because what it shows can be seen and verified.


Some of the greatest benefits from science have come in the field of medicine and health. Thanks to science, most of us have a chance to live much longer, on average, than humans used to. Scholars tell us that when Jesus was crucified at about age 33, he was already older than 90% of the people in his society. Infant, maternal, and childhood mortality have dropped dramatically. Modern science-based medicine has saved my 23-year-old son’s life. Twice.


Of course, the Church today still encourages us to connect with the saints and has no problem at all with the idea of putting our children under the protection of a saint or asking saints to join us in prayer for our children’s health and safety. I certainly prayed and welcomed prayers for my son during his recent life-threatening battle with cancer. What’s different today is that the Catholic Church, which, on the whole, has embraced science, also expects us to take our children to doctors and to take advantage of what science-based medicine can do. 


And that leads me to a topic in Catholic Digest that got a small but very vocal group of readers angry. In April we published some information about vaccine safety from the American Academy of Pediatrics, and the responses came in quickly. They accused us of bias, of ignoring how vaccines cause autism, and of being in the pocket of big pharmaceutical companies. Others suggested that doctors have a vested interest in not telling people the truth about vaccines, and some accused us of not really being Catholic because, as one writer put it, we didn’t say that “vaccines are full of aborted babies.”


These comments show why the editorial team of Catholic Digest wanted to address vaccines in our Be Well column in the first place. Vaccines have been one of the greatest advances in human health, ever, and yet it seems to us that loving parents who only want what is best for their children are being scared these days by voices that appear to be well stocked with emotion, but extremely light on evidence. This is leading some parents to not vaccinate their children, allowing the real possibility of serious disease returning to affect their own children and other vulnerable people in our society.


I’m glad my son was born before all this fear developed, because I’m sure it would have affected me. I don’t blame parents for being scared. No good parent wants to do anything that would put their child at risk for anything. And when people are telling you that you’re poisoning your child and maybe giving them autism, you listen. But what baffles scientists and most doctors is why people are being swayed by arguments that seem to have so little evidence behind them or that the great majority of scientists in this field see as grossly distorting the facts.


I’m not a scientist, and I won’t bore you with my attempts to sound like one. There are many reports from responsible groups that already summarize the evidence much better than I could anyway (see the links at the bottom of this letter). I’d just like to respond to some of the comments made to us:


1. What about equal time for opposing views?

 “I am so disappointed that Catholic Digest chose to show only one side of this issue,” one reader wrote.  Believe me, I never like to disappoint a reader, but on the question of vaccine safety and autism, we honestly don’t see a valid “other side.” Vaccines are studied carefully and tested thoroughly, and the FDA and Centers for Disease Control keep track of all reported side effects — and yes, there are some side effects, but the serious ones are very rare. The evidence clearly shows that vaccines are much safer than catching the diseases they prevent. Everyone may be entitled to their own opinion, but not all opinions and beliefs are equal (and that’s why the Church warns about relativism). In this case, as responsible editors, we saw no choice but to go with the opinions that actually had strong research and evidence behind them.


2. What about autism?

A mom wrote: “If you could walk a mile, no, just twelve inches, in the shoes of a parent with an autistic child….” No, I don’t have an autistic child, but someone near and dear to my heart does, and I’ve seen how autism has devastated that child’s (now young adult’s) life and affected his entire family. I cannot imagine the grief, heartache, and exhaustion that a parent with an autistic child experiences every day. Were I in that situation I know I’d want to know the cause and how to fix it. And if my child started to show autism symptoms soon after a vaccine shot, that shot would be my first suspect.


But study after study after study has found no link between vaccinations and autism. No link at all. And the 1998 study that did so much to spark the idea that vaccines led to autism has been retracted by most of its authors and repudiated by the medical journal that published it, because the data it used to reach its conclusions are false. People still clinging to their belief in a connection between vaccines and autism have science squarely against them and may even be diverting resources away from good research into the real causes and cures.


3. Can doctors be trusted?

One person commented, “So we are to go on the word of the profession that makes part of their living by giving vaccinations to most of the population?” I’m puzzled by this argument. Would this person say we believe in Jesus because of the word of a priestly class that stays in business by exhorting us to believe in Jesus? Of course doctors and scientists get paid—though pediatricians, as I understand it, are generally near the bottom of the physician pay scale. I bet they could increase business substantially by letting kids get these diseases. The competence of doctors may vary widely, but not one I’ve ever met wants sick kids. Period.


Distrust and suspicion are facts of life today. Our heroes have betrayed us, our government and institutions have let us down. reports that 90% of forwarded emails on politics contain substantial lies and distortions. So why should we trust science?  Sure, scientists can be as crooked and biased and sloppy as the rest of us. But science at least has self-correcting mechanisms: Other scientists try to replicate results; methodology can be questioned; conclusions can be tested, and confirmed or repudiated. Without this careful, long-term scientific process, we’re left believing only what we want to believe. Without it, I fear we have only the modern equivalents of the shrine of St. Guinefort — and why, exactly, are they worthy of our trust?


4. Vaccines and abortion: What’s the truth?

This one stings the most: some persons said a real Catholic would have reported that “vaccines are full of aborted babies.” No, they are not. However, unlike most of the arguments anti-vaccination proponents make, this distortion has a connection to fact — one we didn’t know when we published the article. Here’s what we’ve learned:


The attenuated viruses used to make vaccines need to be grown in a culture. Some vaccines, like the seasonal flu vaccine, are grown in chicken embryos. Others are grown in cells taken from monkeys or rabbits. With vaccine technology as it now exists, some safe and effective vaccines can only be grown in cultures of human tissue. So a few important vaccines — rubella, chicken pox, hepatitis A, and one of two rabies vaccines — are grown in cell cultures whose ancestors, many cell generations ago, were taken from three babies who were aborted at different times and places in the 1960s. These babies were not aborted to make vaccines; in fact, no child has ever been aborted for vaccine production, and no aborted fetal tissue, or even tissue descended from the cell tissue of an aborted child, is in the vaccine itself.


This is still a very uncomfortable thing for Catholics. Both the Congregation for the Doctrine of the Faith and the Pontifical Academy for Life have issued statements on it. The Church says that abortion is a grave evil and using cells that came from cells from an abortion to develop a vaccine is morally problematic. But even the gravity of this situation does not shake the clearly pro-vaccine stance of the Church. As Catholics, says the Vatican, we must protest the use of these cell lines and lobby and pressure pharmaceutical companies to develop, if it all possible, new cell lines from non-illicit sources. (The Vatican acknowledges that developing these new cell lines would be a tricky and very costly undertaking.) But, says the Pontifical Academy for Life, “the burden of this important battle cannot and must not fall on innocent children and on the health situation of the population — especially with regard to pregnant women.” If no safe, effective alternative vaccines exist, says the Church, it is lawful to use these vaccines if danger to the health of children exists or to the health of the population as a whole. 


And medicine knows that such danger certainly does exist. Anyone old enough to remember when these illnesses ravaged the human race would never want to see them come back. Studies have shown that in areas where vaccination levels have dropped, the diseases quickly return. And there are children too young to be immunized, and persons who for medical reasons cannot be immunized. These persons depend on what is called “herd immunity” — that the community around them is immunized and thus will not infect them. Weaken that herd immunity, and we put many people at risk. Catholic faith has a strong communal dimension: We are to care for one another and especially for the poor and vulnerable among us. Keeping herd immunity strong is one crucial way to do that.


So Catholic parents who are upset about the origins of these vaccines, and therefore choose to not vaccinate their children, have only escaped one horn of the dilemma. They have not escaped their duty to protect their child and other vulnerable persons in society. As the Pontifical Academy for Life has stated, “This is particularly true in the case of vaccination against German measles, because of the danger of Congenital Rubella Syndrome. This could occur, causing grave congenital malformations in the fetus, when a pregnant woman enters into contact, even if it is brief, with children who have not been immunized and are carriers of the virus. In this case, the parents who did not accept the vaccination of their own children become responsible for the malformations in question, and for the subsequent abortion of fetuses, when they have been discovered to be malformed” (emphasis added). We are responsible for one another. Our decisions carry consequences, no matter what we decide.


It’s never easy to be a parent, and it’s getting harder by the year. In regard to vaccines, I hope all parents will do what they think best, both for their child and for the community. And in their decision-making process I hope they will pay close attention to science and the teaching of the Church on these matters — without their guidance, I fear we have nothing to turn to but the modern-day St. Guineforts, and our own desire to believe in them.





A good summary of MMR vaccine risks and safety from the CDC can be found here:


A summary of the studies researching the alleged connection between autism and vaccines can be found here:



Detailed information about the origins of vaccines grown in cell cultures originally taken from aborted fetal tissue can be found at:


Statements made by the Church about vaccines and abortion can be found at: (number 35)



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