Why Are Fetal Cells Used to Make Vaccines?

Dr. Paul Offit explains why fetal cells were used to make some vaccines and addresses religious concerns related to their use.


Why are fetal cells used to make vaccines?

Paul Offit, MD: So, to understand that, you sort of need to go back in time. In the 1950s there was a polio vaccine that was made using monkey kidney cells. It was the vaccine that was made by Jonas Salk, where he took poliovirus, grew it up in cell culture, purified the virus, and then killed it with a chemical. And, similarly, with Albert Sabin, he made a vaccine by growing the virus up in monkey kidney cells.

The problem was is that those cells, as we found out later, were contaminated with a virus called simian virus 40, or SV40. Now, although this virus was found to potentially cause cancer in experimental animals, it never caused cancer in people. Studies done five years later, eight years later, 15 years later, 30 years later showed that those children who had gotten these vaccines, which were potentially contaminated with this monkey virus, never developed cancer.

So, it ended up not being a problem, but it scared people. And when people got scared there, what they decided to do instead was to use cells from what had been pregnancies that had been terminated, because there were advantages to using these human cells. 1) Human cells are better able to grow human viruses, not surprisingly. 2) Human cells that are obtained from these pregnancies that had ended were, we knew were sterile. We knew that those cells didn't contain any contaminating viruses or any contaminating bacteria. So, that was the advantage of using those cells.

So, there are several vaccines that are made using those cells that were obtained from pregnancies that had been terminated. The rubella vaccine, or German measles vaccine, is one example. The hepatitis A vaccine is another example. The chickenpox vaccine is the third example, and then one of the rabies vaccines. So that's true.

Now, some people feel, understandably, that these cells were obtained from pregnancies that had been terminated violate their religious beliefs. I mean, especially among Catholics for whom abortion is a sin, a sin worthy of excommunication, where you then can't participate in the sacraments of the Catholic Church. So, this issue has gone then before the major policymaking body of the Catholic Church, called the Pontifical Academy for Life. This was years ago. At the time Joseph Ratzinger was the head of the Pontifical Academy for Life. He eventually became Pope Benedict the XVI. But at the time when he reviewed this, he said that it was still important for Catholics to get these vaccines because the Catholic religion, like all faith, believes in health and believes especially in the health of children and the health of families. And because vaccines provide that health, he then recommended that those who were Catholics could still reasonably receive these vaccines.

So, it's an understandable concern. But the fact is, is that if the issue is a religious one, it has been, I guess, deemed OK or acceptable by the Catholic authorities, specifically the Pontifical Academy for Life.

Related Centers and Programs: Vaccine Education Center

Last Reviewed on Feb 25, 2022