Zagreb, December 20, 2020

Dear colleagues,

I see that the coronavirus vaccines have caused great alarm among the Catholic world, which I understand and justify. Each new phenomenon should be carefully considered before usage, including new vaccines. But as physicians (and scientists) we can’t forget that the core of our vocation is to help the sick and protect the health of the population.

The Catechism of the Catholic Church reminds us that life and physical health are precious gifts that God has entrusted to us. We should take reasonable care of them, considering the needs of others and the common good (see: CCC 2288) while  the Congregation for the Doctrine of the Faith make a clear distinction in the relevant documents between the moral responsibility of producers and scientists using morally problematic biological material and the moral responsibility of recipients of specific vaccines and medicines (see: Dignitas Personae). Therefore, the intention of our Society was to unite these two views in the Statement released last week: our professional obligation to help the others (and clarify some prejudices about vaccines) and to encourage the usage of those solutions that are not contrary to the Catechism of the Catholic Church.

Although public debates sometimes rely on generalizing that all COVID-19 vaccines are associated with elective abortion and, moreover, contain parts of aborted fetuses, the available data suggest that some vaccines have nothing to do with human fetal cells, others were used by researchers only for testing within laboratory tests prior to the start of human testing and production, while historical human fetal cell lines are used in the production of some vaccines.

Cells derived from elective abortions have been used since the 1960s in production of many vaccines, some of them still in use (e.g. against rubella, chickenpox, hepatitis A, polio…). These cells are also used to produce approved drugs against a variety of diseases, including hemophilia, rheumatoid arthritis, cystic fibrosis…  I don’t see that their usage is of some concern in the media.

Both cell lines used for COVID-vaccines were developed in the laboratory. These cell lines are “historical”, they are not normal human cells, since they grow and are cultivated for years in the laboratory. These cells have been altered so that they can continually multiply in order to be used for research and production of drugs and vaccines. 

It should be noted that millions of human lives have been saved with the help of drugs and vaccines produced on these cell lines. (Perhaps this can also serve as a consolation for the lost lives of those aborted children: their deaths, although violent and unjust, were not in vain.)

From a moral perspective, those vaccines that have nothing to do with abortion, such as the vaccine developed by Sanofi (under development), are always allowed to be used. For vaccines that use historical human fetal cell lines, there is a difference between those that use them only for pre-testing (Pfizer, Moderna), and those that use them in the manufacturing process itself (AstraZeneca, Johnson & Johnson). For Pfizer’s and Moderna’s vaccines, historical human fetal cells were used in pre-production studies only and not by the manufacturer, while not in the process of vaccine production for human administration.

Regarding Moderna and its mRNA-1273 vaccine, it was made without the involvement of fetal cell culture HEK 293. During the search for a gene construct that would serve as mRNA, among the various constructs existing in the literature, Moderna opted for the one that was earlier, and from some other companies, published as adequate, and they opted for that nucleotide sequence. 

The Charlotte Lizier Institute considers Moderna vaccine ethically correct from the standpoint of Catholic morality (see:

There is another article discussing Moderna’s vaccine (see: The Charlotte Lozier Institute (CLI), research arm of the pro-life Susan B. Anthony List, has listed the Moderna vaccine among the “ethically uncontroversial CoV-19 vaccine programs” along with development projects from Inovio Pharmaceuticals, Sanofi & Translate Bio, Pfizer and BioNTech, Novavax, and Merck/IAVI. According to CLI, two vaccine candidates are the product of unethical programs – those being developed by the University of Oxford and AstraZeneca, and by Johnson&Johnson and Janssen Res. & Devel., Inc.

On the straightforward question of whether the Moderna vaccine is being produced from cell lines from elective abortions, Dr. John Brehany, director of institutional relations at the National Catholic Bioethics Center, said “it appears that the answer is no.” Vaccines work use a weakened version of a disease, grown in laboratory  cell lines, in order to inoculate someone against the disease. With some common vaccines, such as those used to fight chicken pox and measles, mumps, and rubella (MMR), the cell lines of babies who were aborted decades ago are used to grow the weakened diseases. But the Moderna vaccine works in different way than most vaccines. Its method of innoculation “is not based on using cells at all in production,” Brehany said. The Moderna vaccine relies upon a spike protein from SARS-CoV-2 to induce the production of antibodies in the recipient, instead of a weakened version of the disease. The gene sequences for the spike protein were determined to be a good candidate for producing a vaccine. Non-Moderna scientists had initially made DNA vectors with the gene sequence of the spike protein, and injected them in HEK-293 cells to produce the spike protein. That work was studied and evaluated by experts at NIAID and the University of Texas, who determined that the spike protein was a good candidate for testing. Moderna was not involved in the DNA construction nor was it involved in the evaluation of the construction.

Thus, Brehany said, while the company has some association with the use of cell lines from elective abortions, it is not responsible for that use, and its vaccine was not produced using those HEK-293 cells.

Another source (FactCheckNI: summarizes that no COVID-19 vaccine contains cells from aborted fetuses. A replica cell line from a fetus aborted in 1973 was used to develop the AstraZeneca/Oxford University vaccine. However, the vaccine itself does not contain fetal cells. New mRNA vaccines, such as those being developed by Pfizer and Moderna, are synthetic vaccines, sequenced on a computer in a lab, and do not use fetal cell lines in their production.

According to the article (COG/Supplementary Matherials) Moderna’s vaccine has only a literature link to the HEK-293 cell line, because the nucleotide sequence of the spike protein gene has been published somewhere, and this has served as a choice of Moderna’s vaccine sequence.

But there are no cell cultures anywhere in the production of the vaccine.

Regarding moral aspects of vaccines prepared from cells derived from aborted human fetuses, the Pontifical Academy for Life in 2005. (see: Pontifical Academy for Life. Moral reflections on vaccines prepared from cells derived from aborted human fetuses. Natl Cathol Bioeth Q. 2006 Autumn;6:541-37.) stated that “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.” So, they are morally justified as an extrema ratio due to the necessity to provide for the good of humans.

The view from the other document issued by the Pontifical Academy for Life in 2017 (see: is that “it should be noted that today it is no longer necessary to obtain cells from new voluntary abortions, and that the cell lines on which the vaccines are based in are derived solely from two fetuses originally aborted in the 1960’s.” It also said that “the cell lines currently used are very distant from the original abortions and no longer imply that bond of moral cooperation indispensable for an ethically negative evaluation of their use. Hence, we believe that all clinically recommended vaccinations can be used with a clear conscience and that the use of such vaccines does not signify some sort of cooperation with voluntary abortion. While the commitment to ensuring that every vaccine has no connection in its preparation to any material of originating from an abortion, the moral responsibility to vaccinate is reiterated in order to avoid serious health risks for children and the general population.”

In conclusion, as stated in the Statement of the Catholic University of Croatia (see:“it is important to keep in mind that we are in a very sensitive period of human civilization and in an even more sensitive area of our attitude towards life. Therefore, the fear and concern for respect for life from conception to natural death is understandable and justified, which should be unconditionally respected, not allowing any act of endangerment. However, the mentioned principle of proportionality, the position of the Pontifical Academy for Life on historical distance regarding participation in the evil of the other and the danger to health and life, especially of the most vulnerable groups, help us to question our state of conscience and faith even more clearly, avoiding any form of fundamentalism, self-confidence and indifference.

And my personal attitude: of course, I don’t want to die of COVID-19, but I’m not afraid of it as the average person. After all, if I were so scared, I wouldn’t choose my profession in which I am exposed to infection on a daily basis. But today when I think about getting vaccinated or not, I primarily feel obligated to get the vaccine to protect vulnerable people around me, not myself. And that’s why I’m going to do it. Of course, I want to be vaccinated with a vaccine that is produced in a permissible and moral way. But until such vaccines are available to everyone, I understand those who will be vaccinated with other vaccines. I don’t think that by that act they automatically support abortion, they only care about their own health and the health of others. There are many more effective ways to fight abortions.

I hereby wish you all a Merry Christmas!

Prof. Rok Čivljak, MD, PhD

President of the Croatian Catholic Medical Society