Why the CDF 'Note on the Morality of Using Some Anti-Covid-19 Vaccines' Suggests a Moral Obligation to Receive SARS-CoV-2 Vaccines

November 16, 2021
Feature Article
Peter J. Cataldo, Ph.D.

The Congregation for the Doctrine of the Faith in its Note on the Morality of Using Some Anti-Covid-19 Vaccines stated that "... practical reason makes evident that vaccination is not, as a rule, a moral obligation and that, therefore, it must be voluntary" (n. 5).1 This statement has been interpreted to mean that the CDF concludes there is no moral obligation to receive the currently available SARS-CoV-2 vaccines and that institutional and governmental "mandates" are ethically unacceptable. I will argue that there is no basis for this interpretation and that the CDF Note does entail a moral obligation to receive the vaccines by those for whom a vaccine is not medically contraindicated and that it does not rule out the moral legitimacy of mandates.

To interpret the CDF statement as precluding a moral obligation to receive the vaccines conflates what the CDF regards as a general rule or obligation in principle with moral obligation on the individual level.2 Similarly, the CDF use of "vaccination" in the statement refers to the act of vaccination in general, not to use of a specific vaccine in a specific set of circumstances. Thus, the fact that in principle there is no moral obligation for vaccination per se does not preclude a moral obligation to be vaccinated in particular situations. Similarly, the fact that it might be morally valid for individuals to refuse vaccinations in conscience generally, does not entail that there is no moral obligation for vaccination with specific pandemics, such as SARS-CoV-2, even though some individuals might refuse in conscience. Simply because individuals are free to refuse in conscience does not mean that they are not under a moral obligation to be vaccinated, or that the CDF has excluded the possibility of a moral obligation.

This important distinction between a moral obligation or lack of one in principle with an obligation or lack of one in particular circumstances is analogously evident in the distinction between the in principle moral obligation to receive food and water and the absence of this obligation as assessed in the particular circumstances of an individual patient for whom medically assisted nutrition and hydration would be ethically disproportionate.3 A moral norm considered in principle or in general does not necessarily apply in each and every individual case due to the particular circumstances of the case. This is a central premise, for example, in the principle of the double effect upheld in Catholic teaching and tradition where conditions are presented for assessing whether what is a moral obligation in principle applies in a particular case of an act that has both good and bad effects. Ultimately, the distinction is rooted in the classic distinction between something considered per se according to its essence and the same thing considered per accidens or how it is affected by its accidental features and particular circumstances.4

The CDF Note shows that while it acknowledges in principle that there is no moral obligation for vaccination, the moral status of vaccination in the particular circumstances of SARS-CoV-2 can be regarded as obligatory. The CDF statement about vaccination considered in principle should not be taken in isolation from all the other affirmations that the CDF makes about moral duties and responsibilities related to individuals and the common good in particular situations such as SARS-CoV-2. This is the implication from several affirmations made by the CDF. First, the CDF reaffirms that there are differing degrees of responsibility in the case of vaccines developed using cell lines created with cells from tissue obtained from abortions and that a primae facie moral prohibition does not exist in the case of those who receive such vaccines. Second, the CDF points out that the grave danger posed by SARS-CoV-2 is a harm that is morally greater than any remote connection to abortion and finds that this proportionality is morally decisive. Third, the CDF also affirms that the morality of vaccination is inextricably tied to ("depends on") the moral duty to protect one's own health and the duty to pursue the common good. The implication is that because there is a moral obligation to protect one's health and to pursue the common good, there is a moral obligation to use safe and effective vaccines in this particular case to fulfill these duties in the face of the grave danger of SARS-CoV-2, notwithstanding any lack of an obligation for vaccination in principle. Fourth, The CDF Note states that "the common good may recommend vaccination." It is a legitimate interpretation of this statement that since there is a moral duty to contribute to the common good, and considering that in some situations vaccination is the best means to stop or prevent an epidemic, the moral permissibility of vaccination is at the same time a moral necessity for preserving the common good.

The term, "may recommend," as it is used in connection with the common good here connotes the permissibility of legitimate authorities enacting universal measures appropriate to and determined by that good which is held in common. Hence, "may recommend" does not have the meaning of a suggestion to individuals but refers to the moral legitimacy of institutional and governmental measures, like vaccination requirements, that are appropriate to the universal nature of the common good. Finally, the CDF states any connection to past abortions is not illicit cooperation but passive material cooperation and that "the moral duty to avoid such ... cooperation is not obligatory if there is a grave danger, such as the otherwise uncontainable spread of a serious pathological agent — in this case, the pandemic spread of the SARS-CoV-2 virus that causes Covid-19" (n. 3). The CDF is again showing how moral responsibilities are not reducible to a consideration of moral obligation considered in principle and that such in principle norms must be evaluated in light of particular circumstances in order to determine an individual's responsibilities. Given the particular circumstances of SARS-CoV-2 and given the other moral duties acknowledged by the CDF, the lack of an obligation to avoid passive material cooperation may be interpreted as being corelative with the positive obligation to be vaccinated.

Moreover, any stated or implied moral obligation to receive SARS-CoV-2 vaccines made by the Church is not about particular institutional or governmental "mandates." Rather, any support by the Church for vaccination prescinds from the issue of how mandates may be configured and is focused instead on the status of the moral obligation for vaccination precisely as a moral obligation. Given this fact and given what has been explained about the relation between a moral norm in principle and moral obligations in individual situations, there is no leap whatsoever from what is morally permissible in principle to what is morally obligatory in a particular situation like SARS-CoV-2.

Claims are made that the data about SARS-CoV-2 vaccines is unsettled or that there are unanswered medical questions about the vaccines and that this purported fact is morally sufficient for avoiding the vaccines. However, the CDF asserted that these vaccines can be used in good conscience with an appropriate level of certitude.5 Such claims lend themselves to the false idea that Catholic moral teaching and tradition require absolute or one hundred percent certitude for human action. When it comes to the contingent and changing matters of human action, Catholic teaching and tradition have always recognized that moral or prudential certitude about the outcomes of an action is what is morally required, not absolute certitude. The Catholic tradition generally defined certitude or a certain conscience in moral matters as the lack of prudent fear of error in making a judgment that a particular act is either morally good or is immoral. The moral certitude of conscience ought to admit the possibility of error but excludes any reasonable doubt. The scientific evidence on the available vaccines for SARS-CoV-2 removes reasonable doubt about their safety and efficacy. In addition, and as attested by the CDF, there is no basis for reasonable doubt about any unethical connection to the past abortions from which cells were originally obtained to build the cell lines used in the development of the vaccines. Hence, consistent with Catholic moral teaching and tradition, a properly informed conscience on these vaccines can attain the moral certitude required for conscience to judge that taking them is morally acceptable. If this moral certitude did not exist for conscience to act on, the CDF and Pope Francis would not reach the conclusions they have about the moral acceptability of the vaccines.6

The moral obligation to act with a properly formed conscience is an obligation equally important as the obligation to follow one's conscience (see Catechism of the Catholic Church, ns. 1776–1794). Catholic teaching recognizes that the proper formation of conscience in part relies on human reason; in the context of vaccines for SARS-CoV-2, the resources of reason on which the formation of conscience depends include peer-reviewed scientific evidence presented by legitimate scientific sources and authorities. The moral obligation to obey one's certain conscience is applicable if, and only if, one has a certain conscience that is not negligently ignorant of the facts. While Catholic teaching requires that the person follow a certain judgment of conscience, this obligation does not include a certain conscience that is based on negligent ignorance of the facts. The only erring judgement of conscience to which one is still morally bound to follow is that judgement in which one is excusably ignorant of the facts.7 In such cases the person is not morally culpable for any wrongdoing that might result, even though objectively the wrongdoing is still committed. There is an essential difference between a conscience based on true knowledge and one based on inexcusable ignorance of the facts.8 Negligent or "vincible" ignorance of the facts regarding SARS-CoV-2 abounds in today's climate, which places a special obligation on theologians and ethicists to attend to this dimension of Catholic moral teaching and tradition on conscience.9

The fact that the CDF did not explicitly prescribe a moral obligation to receive the SARS-CoV-2 vaccines in its Note does not entail that one does not exist, or that the CDF does not recognize the obligation. The only way to conclude that the CDF does not implicitly recognize a moral obligation to the receive the SARS-CoV-2 vaccines currently available is to isolate its acknowledgement of the lack of an in principle obligation for vaccination in general from all of the other moral affirmations it makes, and to ignore the long-standing distinction between norms considered in principle on the one hand and on the other their assessment in particular circumstances. A moral obligation to receive the SARS-CoV-2 vaccines is completely compatible with what the CDF states about vaccination in general and with Catholic teaching and tradition on conscience and moral certitude.

Peter Cataldo, Ph.D.
Senior Vice President, Theology and Ethics
Providence St. Joseph Health

[email protected]


  1. Congregation for the Doctrine of the Faith, Note on the morality of using some anti-Covid-19 vaccines (December 21, 2020),
  2. See, for example, The National Catholic Bioethics Center, "NCBC Statement on COVID-19 Vaccine Mandates,"
  3. See United States Conference of Catholic Bishops, Ethical and Religious Directives for Catholic Health Care Services, Sixth Edition, n. 58, See also Congregation for the Doctrine of the Faith, Commentary (August 1, 2007), n. 4,
  4. See, for example, St. Thomas Aquinas, Commentary on Aristotle's Physics, bk. II, lect. 6, n. 3; Summa Theologica, I, q. 49, a. 1 c., ad 2, 3, and 4; ST I-II, q. 20, a. 5.
  5. See the Note, n. 3, and see, for example, data from the Centers for Disease Control and Prevention (CDC).
  6. See a video message of Pope Francis on how receiving SARS-CoV-2 vaccines is an act of love,
  7. See Aquinas, ST I-II, q. 19, a. 5, a. 6.
  8. See Jason T. Eberl, "Vaccine mandates are coming. Catholics have no moral reason to oppose them," America The Jesuit Review (August 10, 20221),
  9. On the moral obligations of those producing materials on Catholic teaching about vaccine exemptions see M. Therese Lysaught, "Catholics seeking ‘religious' exemptions to vaccine must follow true church teaching on conscience," National Catholic Reporter, September 21, 2021,

Reflection Questions

  1. How does the Church use the phrase "in principle" as it relates to moral obligations?
  2. Do you agree with the article's premise that a moral obligation to receive the COVID vaccine is compatible with the CDF statement?
  3. What are some other moral obligations we have as Catholic faithful that are not explicitly stated in a document?

  • Peter J. Cataldo, Ph.D.