In healthcare, there are few topics that generate more controversy in our current climate than the topic of vaccinations. This is a perennial issue of concern both for the young and old as there is a great deal of material readily available online that suggests vaccines are either one of the greatest goods or greatest evils of modern medicine. While all will admit that the information available online can be contradictory, it is very difficult for most patients to identify the best path forward. What is a Catholic to do?

While the first successful vaccine was developed in 1796, it was not until the Salk Polio vaccine of the 1950s that routine vaccination became a right of passage in American pediatric medicine. In just a handful of years, annual cases went from a high in 1952 of 57,000 (with 21,000 incidences of paralysis) to about 5,600 cases in 1957. This continued to decline until the last “wild” case of polio was transmitted in 1979. While polio was the most analyzed and documented study of the effects of a vaccine, a similar story occurred with many of the other diseases that we vaccinate for today. As a public health initiative, the use of vaccination to limit the spread of a contagious disease has been nothing short of a major success.

However, the wholly positive outlook on vaccines changed around 1998 when Dr. Andrew Wakefield published an article in the Lancet medical journal suggesting that autism could have been related to vaccination. Ultimately, this article was retracted and Dr. Wakefield’s medical license was revoked because the study was performed in a way that was neither ethically nor scientifically sound. Subsequently, the link between autism and vaccines has been evaluated and deemed to not exist in multiple meta-analytical studies. Despite this, vaccines have continued to be viewed by many with grave concern that stemmed originally from the disingenuous article from 1998.

The concern of Catholics regarding vaccination has continued to increase as well with more attention being given to the role of abortion in vaccine development. Vaccines are available to give immunity to many bacterial and viral diseases; and while bacteria can be grown in a petri dish, the viral illnesses that we have vaccines for require a cell/cell line for their development.

Cell lines

For several viral vaccines (MMR and Hep A among others) the cell lines that continue to be used in vaccine development came from elective abortions in the 1960s and 1970s. “Cell lines” that can continue somewhat indefinitely were begun with embryonic tissue from these abortions, and these vaccines, unfortunately, continue to be developed with these cell lines today. As Catholics, we are right to reject abortion in every instance as an assault against human dignity and rightly question any technology that depends on or benefits from abortion.

Thankfully, in 2005, the Vatican weighed in on the ethical duties of Catholics regarding vaccines that are prepared with cells derived from aborted human fetuses. In summary, there exists an unfair choice for parents; either immunize with these “tainted” vaccines or risk contracting these diseases and potentially spreading them to others at risk, especially the vulnerable who cannot receive the vaccine themselves.

It was stated that “it is right to abstain from using these vaccines if it can be done without causing children, and indirectly the population as a whole, to undergo significant risks to their health. However, if the latter are exposed to considerable dangers to their health, vaccines with moral problems pertaining to them may also be used on a temporary basis. The moral reason is that the duty to avoid passive material cooperation is not obligatory if there is grave inconvenience. Moreover, we find, in such a case, a proportional reason, in order to accept the use of these vaccines in the presence of the danger of favoring the spread of the pathological agent, due to the lack of vaccination of children.”

Taking action

The greatest emphasis, however, was placed on the duty of the faithful to publicly advocate for the production of ethically acceptable vaccines that would successfully protect society from these diseases without relying on cell lines from an abortion to continue producing the vaccine. As such, I would like to invite readers to use my template for a letter below to write the pharmaceutical companies who manufacture these vaccines and urge them to develop ethically sourced vaccines.

Over the last many weeks, the American public has rightly been taking drastic measures to protect society from the coronavirus. In spite of these efforts, many have suffered and died from this disease. It was only a few generations ago, that epidemics were commonplace and the fear, which we recently have been experiencing was widespread. Just as we have a duty now toward the common good and in solidarity with our neighbor to do what we can to stop the spread of the coronavirus, I would assert that we have the same duty to prevent the spread of vaccine-preventable diseases insofar as we are able with fighting publicly for a rejection of any cell lines obtained from abortion. Please consider obtaining the recommended vaccines for yourself and your family and writing the vaccine manufacturing companies to urge the development of ethically sourced vaccines.

Dr. Andrew J. Mullally, M.D. is a physician with Credo Family Medicine in Fort Wayne, Indiana.

Sample letter

To Whom It May Concern:

I am writing today to protest your ongoing use of aborted fetal cell lines (WI-38 and MRC-5) in vaccine production. The use of cell lines developed in this way is unethical and renders you complicit with abortion in general and the immoral use of these embryos for medical purposes in particular. I am firmly opposed to abortion and am greatly disappointed with your ongoing facilitation of this evil.

As a person who is greatly opposed to abortion, I have a grave responsibility to use alternative vaccines when possible. However, for many vaccines (MMR, HepA, Polio, and Rabies among others), there are no currently available alternatives. As a patient who desires the protection offered from immunizations, you have put me in an unfair and unjust position where I am coerced to choose between passive material cooperation with this evil or going without protection against very serious and preventable diseases. Many, many people are forgoing receiving these vaccinations because of their unethical origins. While this hurts them and our community, they feel that they have no choice. However, this could be resolved by your corporation!

I would like to sincerely implore you to develop ethically sourced vaccines that do not require the use of aborted fetal stem cell lines. If this were done, I know that many patients, including myself, who oppose abortion would wholeheartedly switch to the sole use of that vaccine over the current unethical alternatives. This has already been seen in the market with the nearly universal adaption of Shingrix (GSK) taking market share from Zostavax (Merck) after its introduction. I would like to make a public commitment that when ethically produced alternative vaccines become available, I will actively promote and encourage the preferential use of these vaccines by all.


Andrew J. Mullally, M.D.

Merck & Co., Inc.
Vaccine Customer Center
770 Sumneytown Pike
West Point, PA 19486-0004
877.VAX.MERCK (877.829.6372)

Sanofi -Aventis
Sanofi US
Sanofi Building D, Corporate Dr
Bridgewater Township, NJ 08807
1-800-VACCINE (1-800-822-2463)

Philadelphia Navy Yard
5 Crescent Drive
Philadelphia, PA 19112