There are many false and distorted claims being made about vaccines and cell lines from an aborted fetus. What is certain is that no vaccines contain any cells that were ever part of an aborted fetus (or any fetus).

What we are discussing is cell lines. A small sample of cells were taken from the kidney of an aborted fetus in 1973. These cells were grown in a lab and developed into a continuous line of cells, called HEK-293, which are then used for research. These cells were grown in a petri dish (or similar container); there, they replicate by division. The cells divide in order to produce the next generation of cells. A cell line such as HEK-293 divides about once every 24 to 48 hours [1]. So the cells that are used in lab testing today, over 45 years later, are thousands of generations subsequent to the small sample of kidney cells taken from an aborted fetus in 1973. None of the molecules or cell parts or cells from HEK-193 today were ever in a fetus. These cells are thousands of cell-generations subsequent to that person’s kidney.

The abortion that took place in 1973 was a grave sin. However, it was not chosen for the sake of research. The researcher’s actions occurred after the fact. The use of fetal cells from an aborted fetus is also gravely immoral. But we cannot change that past act. And what we have today is a complex moral situation.

Given the current state of medical technology, it is possible for these cell lines, which began with cells from an aborted fetus, to be replaced with cells from an adult who is a willing donor. This can and should be done. However, it would take a few years to develop these several cell lines, and then more than a few years for research studies, using these cell lines, to accumulate such that medical researchers and companies making vaccines could have sufficient certitude that the research based on these proposed new cell lines is reliable. So for the present pandemic, we cannot replace those aborted fetal cell lines. (Another issue is that companies do not wish to invest the time and money in developing new ethical cell lines, when their main concern is profit.)

Given the current situation in research and medicine, that such tainted cell lines are used by many researchers and companies, it is not possible to develop a vaccine or a medication or a treatment that is entirely unrelated to tainted cell lines. Any vaccine relies on a vast number of studies, some of which used these cell lines. Any research paper has dozens of references, and each of those references is a paper with its own list of references. But these aborted fetal cell lines are so widely used that you could not find a study that was not connected to the cell line, at least indirectly. Every vaccine and medication relies on information from a vast number of studies, and many of those studies used these cell lines.

Is it immoral to receive a vaccine when research and development of that vaccine involved the use of aborted fetal cell lines (AFCLs)? No, it is not immoral. The Holy See has repeatedly taught, along with some of the Bishops’ Conferences, that the reception of a vaccine made using aborted fetal cell lines is remote material cooperation, and is therefore moral (as the good of the vaccines outweighs, morally, the remote connection to a past sin of abortion).

However, certain vaccines use AFCLs for the production of the vaccine. For Covid-19, the two vaccines that make use of AFCLs for production are the AstraZeneca (AZ) and the Johnson and Johnson (JJ) vaccines. Other vaccines use AFCLs for testing only, or for experiments at various points in research and development. The way that these cell lines are used for the AZ and JJ vaccines are in production, which has a closer relationship to the vaccine. These vaccines both use an adenovirus to carry the vaccine component (a gene for the Covid-19 Spike protein) into human cells, which then stimulates the human immune system to produce antibodies to that Covid-19 Spike protein.

Adenoviruses are a type of virus which cause the common cold. In the case of the AstraZeneca vaccine, a type of adenovirus that only infects chimpanzees, and not also humans, is used. The virus is the altered so that it can no longer replicate (makes copies of itself). The genes needed for the virus to replicate, and therefore to cause an infection, are removed. So the adenovirus cannot cause an infection in a human person who is vaccinated because is it a chimpanzee disease, and also because its genes for replication have been removed.

Next, the virus’ dna has the gene for the Covid-19 Spike protein added to it. The purpose is to cause this Spike protein to be made by the cells of the person who is vaccinated. The immune system then detects these Spikes and produces antibodies to the Covid-19 Spike protein. The immune system also “teaches” its T-cells to recognize this Spike protein. Then, beginning about 1 to 2 weeks after vaccination, the immune system will be ready to fight off any infection by Covid-19.

The reason for using a modified adenovirus to bring the Spike protein DNA into a human cell is so that the DNA gets to the right place in the human cells, so as to cause the cells to make the Spike protein. But the virus used as a vector to bring that DNA into human cells must be unable to replicate (makes copies of itself). This presents a problem. How do you make many copies of this modified adenovirus, if it cannot replicate?

The answer is that they infect HEK-293 cells with the modified adenovirus. This cell line is modified to contain the genes that allow the adenovirus to replicate, the same genes that were removed from the virus to make it safe to use as a vector for the Spike protein gene. So when those particular cells are infected with the modified adenovirus, it now can replicate, making enough copies of itself to produce millions of vaccine doses. But that HEK-293 cell line is an AFCL; it is from an aborted fetus. The cells in use today are many thousands of cell-divisions subsequent to the aborted fetus. None of those cells were ever in a fetus. But they are derived from a past abortion.

The AstraZeneca vaccines uses the HEK-293 cell line. The Johnson and Johnson vaccine uses a different AFCL, called PER.C6, which is from the retinal cells of a fetus aborted in 1985. But the same principles apply to both vaccines. The cells today in the PER.C6 cell line are thousands of generations of cell divisions subsequent to the aborted fetus, and none of those cells today were ever in any fetus.

The reception of a vaccine produced in this way is still a case of material cooperation. There is no intention to participate in the past sin of abortion. There is no direct participation in that past intrinsically evil act. The morality of the reception of the vaccine then depends on an evaluation of the circumstances, as the intention and moral object are both good. The person intends to receive a vaccine to protect himself and others from harm and death. The moral object of this act of receiving a vaccine is the same, protecting life from harm and death. The connection to the AFCL is less remote, but the connection to the actual sin of abortion is still remote.

In the principles of cooperation with evil, what matters is the moral weight and moral distance of the sinful act and the cooperative act. The act of abortion is still remote, even when the cells, thousands of cell divisions later, are used to produce the vaccine. Accepting the vaccine still in no way involves the person in the sinful act of abortion. And since researchers have ways to make similar cell lines today (e.g. induced pluripotent stem cells), accepting the vaccine does not encourage further creation of a new cell line from an aborted fetus, nor does it encourage abortion for any reason.

Yes, this type of vaccine, actually produced with AFCLs, is less remote than a vaccine which only used AFCLs in research and development. However, the moral weight of protecting lives from a deadly pandemic certainly greatly outweighs this somewhat less remote connection to a single abortion in 1973, which was chosen for reasons unrelated to research.

The mere physical connection to that past act is not what is morally evaluated. If we beat our swords into plowshares, can the plowshares not be used for good because the metal was used to kill in warfare? What matters is not the physical item, in this case cells that were never in a fetus, which are thousands of cell-generations subsequent to that person, but rather the moral connection, which is nevertheless still remote. Similarly, the connection between the killing of persons in war with a sword, and the plowshare made from that sword, is physically proximate but morally remote. Therefore, it is permissible to use the plowshare.

What if you have a choice of vaccines? The mRNA vaccines (Moderna, Pfizer) were made using AFCLs in R&D but not in production. The Johnson and Johnson and also the AstraZeneca vaccines were produced using AFCLs; that is how they make enough of the adenovirus to use in vaccines. Are there any actual fetal cells from the AFCL in the vaccine? No. The vaccines contain the modified adenovirus, harvested from the cell culture using PER.C6 or HEK-293. The cells in question are much larger than the adenovirus, so the separation of the two is not difficult.

Some persons might prefer the mRNA vaccines as they have a more remote connection to the AFCLs. However, it is unlikely that most persons will have a choice. Also, since both vaccines are moral, you are not obligated to choose the vaccines that is more remote. In any act, you are obligated to avoid sin, especially serious sin, but you are not obligated to do what is most perfect, and to avoid imperfection or lesser goods.

Suppose you disagree. Alright, what would happen if everyone took your advice and avoided the JJ and AZ vaccines? The world would have lost a vast number of vaccine doses, the vaccination program would take even longer, and more lives would be lost. This pandemic affects the whole human race. We need every possible dose from each different type of vaccine. Those who reject these vaccines are vastly underestimating the danger this pandemic poses to the human race, and are badly misinterpreting Church teaching on cooperation with evil.

Abortion is not an exception to the eternal moral law. As grave an evil as it is, we should put our efforts into ending abortion, rather than in merely ending the use of cells remotely connected to a past abortion decades ago. If it is not moral to take the vaccine that has the closer, but still remote, connection to a past abortion, then it also would not be moral to fight against the use of AFCLs while tens of millions of abortion take place every year in the world. Why are you not using your efforts to fight against actual abortions occurring at a rate of more than one per second?

I favor laws requiring research companies to make new ethical cell lines from healthy somatic adult cells, using IPSCs and similar techniques. But it will take years to establish these lines and use them in enough different experiments that they can be relied upon for research and production of medicines. Until then, it is moral to use these cells in whatever way is necessary to heal disease, or to prevent suffering and death from disease. Vaccines are generally moral, as they are ordered to do good; therefore, they are not intrinsically evil and are justifiable based on good intention and the moral weight of the circumstances. (The exception would be vaccines ordered to do evil, such as a vaccine that is inherently contraceptive or abortive.)

Ronald L. Conte Jr.