The past year of suffering under the onslaught of COVID-19 has brought with it numerous ethical questions, and the advent of effective vaccines for COVID is no different. Foremost among the questions for those of us who are committed to defending the intrinsic equal dignity of all human beings from conception to natural death are these: in accepting any of the vaccines on offer, is one in any way endorsing or contributing to the practice of abortion, or is one in any way showing disrespect for the remains of an unborn human being? As to the vaccines currently or soon available in the United States, we agree with Bishop Kevin Rhoades, Chairman of the USCCB Committee on Doctrine, that the answer is no. While there is a technical causal linkage between each of the current vaccines and prior abortions of human persons, we are all agreed, that connection does not mean that vaccine use contributes to the evil of abortion or shows disrespect for the remains of unborn human beings. Accordingly, Catholics, and indeed, all persons of good will who embrace a culture of life for the whole human family, born and unborn, can use these vaccines without fear of moral culpability.

Common to the four major vaccines, produced by Moderna, Pfizer, Johnson & Johnson, and AstraZeneca is some use of “immortalized” human cell lines. Ordinarily, cells taken from a body have a limited life span, undergoing only a fixed number of cell divisions before they arrest and die. For ongoing research, scientists prefer to use a “cell line,” or a population of cells derived from a single source that has been modified (typically by some form of genetic mutation) to divide indefinitely in culture. Such “immortalized” cell lines allow scientists to conduct many experiments on cells that are both genetically identical and routinely available in the laboratory.

HEK293 is one such commonly used line.[1] The name “HEK” stands for “human embryonic kidney,” and “293” refers to the 293rd experiment conducted by the scientist who produced the cell line. The embryonic kidney cells were originally obtained from the remains of a deceased unborn child following what appears to be an elective abortion that took place in the Netherlands during the early 1970s. The exact circumstances of the abortion are not known, but the scientists producing the cell line were not directly involved and, crucially, the abortion was not performed for the sake of providing biological materials to researchers.

HEK293 cells are particularly susceptible to the introduction of foreign DNA, and they rapidly became a standard scientific workhorse, that is widely used by both basic scientists and by industry. Although there are currently many modified versions of HEK293s that optimize these cells for specific purposes, all of the HEK293 cells available around the world today were derived from the remains of a single unborn child that was aborted a half a century ago. Importantly, there is no ongoing use of aborted tissue to generate HEK293 cells, to modify these cells, or to maintain them in the laboratory. Thus, the use of HEK293 (and similar immortalized lines) does not create future incentives for more abortions.

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How widely used are HEK293 cells? They are commonly used for testing processed foods produced by companies such as Kraft, Nestlé, Cadbury and others. Indeed, the great majority of processed/packaged food products available for sale in the United States are likely to contain ingredients produced or tested in HEK293 cells.

They are also used as an alternative to animal testing in the cosmetic and pharmaceutical industry. And their use in biomedical research is ubiquitous and has contributed to an enormous number of new medications and medical procedures developed over the last several decades. It thus seems fair to say that in addition to the use of HEK293 cells by the scientific community, nearly every person in the modern world has consumed food products, taken medications or used cosmetics/personal care products that were developed through the use of HEK293 cells in the food, biomedical and cosmetic industries.

The various vaccines have made different uses of the HEK293 cell line, with Johnson & Johnson and AstraZeneca using them for manufacture, Pfizer and Moderna for testing only. But these differences are irrelevant to the following questions:

Do any of the vaccines make more use than others of the mortal remains of unborn children from whom the cell lines were derived? The answer is no; as a matter of scientific fact, no fetal “body parts” are present in these immortal cell lines. The immortal cell lines are artifacts—biological products that have been modified and reproduced many times over, and they do not retain the natural function of the tissue from which they were derived. They are not “body parts” in any meaningful or morally relevant sense.

Does the production and use of any of the vaccines contribute to, cooperate with, or promote any abortion? Again, the answer is no, for the abortions from which cell lines such as HEK293 were derived happened decades ago, and no further fetal tissue is used or needed for the maintenance of these lines.

Common to all pro-life witness is recognition that the apparent elective abortion that led to the derivation of the HEK293 cell line was morally impermissible and involved the unjust taking of a human life. But to repeat, the HEK293 cell line currently used around the globe in scientific research and those like it do not contain the remains of any human being and so its use does not show disrespect for human remains, any more than the contemporary use of products, such as roads or train lines, that were constructed by unjustly enslaved human beings, or use of land unjustly taken, shows disrespect for those victims in the distant past.

As a descriptive matter, some pro-life advocates may prefer to use one vaccine rather than another in order to witness against the evil of abortion, or to signal special respect for the unborn babies whose lives were lost. Again, we agree with Bishop Rhoades that such a choice is a matter for their conscience. But we think it a mistake to say both that these vaccines are morally permissible to use and yet that some ought to be preferred to others. There appears to us to be no real distinction between the vaccines in terms of their connection to an abortion many decades ago, and thus the moral starting point is one of equivalence.

Moreover, there might be good reasons for some persons to prefer or to promote the vaccines, such as Johnson & Johnson, that use HEK293 (and PER.C6) for manufacture rather than testing, namely, that the J&J vaccine requires only one dose, does not require storage at extremely low temperature, and thus may be more useful in reaching remote or otherwise underserved populations. Those who have special reasons to take the J&J vaccine should not, we believe, be led to think that they are choosing something that in other ways is more morally tainted than the Pfizer or Moderna vaccines.

Persons with access to these vaccines have strong moral reasons to take them: in doing so, they build up the herd immunity that will provide the greatest possible protection for the most vulnerable among us, including the elderly, those with pre-existing conditions, some minority populations, and the many other seemingly random victims of severe COVID-19. To be perfectly clear, we are not saying that people are justified in using and promoting these vaccines because the great goods they provide offset the evil of appropriating a prior wicked action. Rather, we believe that there is no such impermissible cooperation or appropriation here. The attenuated and remote connection to abortions performed decades ago and the absence of any incentive for future abortions offer little if any moral reasons against accepting this welcome advance of science.


This brief postscript is to underscore what is already stated explicitly above and to avoid any confusion. By way of background, the statement was meant to offer a comparative ethical analysis of the use of the different COVID vaccines available in light of variations in their production (i.e., using immortalized cell lines in testing versus manufacture). After analyzing the question, we concluded (along with the USCCB and the CDF) that one may choose any of these vaccines to protect oneself or one’s community from transmission of the virus without (1) endorsing the abortion that preceded the development of the cell line (performed for reasons separate and independent such development), (2) incentivizing future abortions, or (3) disrespecting the memory or mortal remains of the baby whose cadaveric tissue was used and modified to create the cell line.[2] Moreover, we concluded that there are not reasons rooted in concerns of moral culpability to choose one vaccine over another based on differences in production.

At the same time, we noted that there are those who share our pro-life commitments who might wish to choose one vaccine over another in order to express their prophetic witness in favor of a culture of life, to show special respect for the lives and memories of unborn children unjustly killed in abortion, and to avoid a coarsening of the moral sense in this context. We observed (with the USCCB) that such people should be free to make such choices as their consciences dictate. However, we were also clear that one is not morally required to make such a choice, and those who do not are not morally culpable.

On the other hand, our statement did not assert that there is a binding moral duty to take any of the vaccines. It did, however, explain why, in our judgment, there are strong moral reasons to do so, given the apparent benefits for vulnerable individuals and communities, and the absence of immoral cooperation or appropriation. The statement did not address the matter of those who wish to express prophetic witness for a culture of life and signal special respect for the unborn by entirely avoiding the vaccine. We would note that the CDF’s December 2020 statement speaks to this matter directly in paragraph 5:

At the same time, practical reason makes evident that vaccination is not, as a rule, a moral obligation and that, therefore, it must be voluntary. In any case, from the ethical point of view, the morality of vaccination depends not only on the duty to protect one’s own health, but also on the duty to pursue the common good. In the absence of other means to stop or even prevent the epidemic, the common good may recommend vaccination, especially to protect the weakest and most exposed. Those who, however, for reasons of conscience, refuse vaccines produced with cell lines from aborted fetuses, must do their utmost to avoid, by other prophylactic means and appropriate behavior, becoming vehicles for the transmission of the infectious agent. In particular, they must avoid any risk to the health of those who cannot be vaccinated for medical or other reasons, and who are the most vulnerable.


Ryan T. Anderson, Ph.D., President of the Ethics and Public Policy Center

Father Nicanor Pier Giorgio Austriaco, O.P., Ph.D., S.T.D., Professor of Biology and of Theology, Providence College

Maureen Condic, Ph.D., Associate Professor of Neurobiology, University of Utah

Father Kevin Flannery, S.J., DPhil, Emeritus Professor of Philosophy, Pontifical Gregorian University

Robert P. George, J.D., D.Phil, D.C.L., D.Litt., McCormick Professor of Jurisprudence, Princeton University

O. Carter Snead, J.D., Professor of Law and Director of the de Nicola Center for Ethics and Culture, University of Notre Dame

Christopher Tollefsen, Ph.D., Distinguished Professor of Philosophy, University of South Carolina

Father Thomas Joseph White, O.P., D.Phil., Professor of Systematic Theology, Pontifical University of St. Thomas Aquinas – Angelicum

Affiliations provided for identification purposes only. This statement was originally posted here and is reprinted with the postscript with permission of the Ethics and Public Policy Center.

[1] We believe that the same analysis applies to the use of the immortalized cell line “PER.C6”, used in the Johnson & Johnson vaccine, derived thirty-one years ago using the remains of an unborn baby following an elective abortion obtained for reasons entirely disconnected to the creation of the line.

[2] “It must therefore be considered that, in such a case, all vaccinations recognized as clinically safe and effective can be used in good conscience with the certain knowledge that the use of such vaccines does not constitute formal cooperation with the abortion from which the cells used in production of the vaccines derive. It should be emphasized, however, that the morally licit use of these types of vaccines, in the particular conditions that make it so, does not in itself constitute a legitimation, even indirect, of the practice of abortion, and necessarily assumes the opposition to this practice by those who make use of these vaccines.” Congregation for the Doctrine of the Faith, “Note on the Morality of Using Some Anti-Covid 19 Vaccines” (December 2020).