Charlotte A. Moser, Assistant Director, and Paul A. Offit, Director, Vaccine Education Center at The Children’s Hospital of Philadelphia

We often get questions about the use of cell lines from aborted fetuses in vaccines. In this article, we will address the issues and provide information about the resources available to share with parents.


The only vaccines that are made in human cells are:

  • Varicella
  • Rubella
  • Hepatitis A
  • Rabies vaccine – the version known as Imovax®

The viruses were grown in cells obtained from elective terminations of pregnancies which occurred in the early 1960s. Since that time, the cell lines have been maintained in the laboratory. No further sources of fetal cells are necessary.

The questions about use of fetal tissues generally fall into one of three categories:

  • Ethics and religion
  • Vaccine safety related to remaining DNA
  • Vaccine safety related to human proteins

Ethics and religion

Christian Science does not believe in using any vaccines; however, when outbreaks have occurred in communities with Christian Scientists, some have agreed to be vaccinated. Their concerns are not related to the use of fetal tissue, but rather to the use of modern medical interventions.

Given the position of the Catholic Church on abortion, some concerns have revolved around the use of cell lines from aborted fetuses. However, reviews by both the Vatican’s Pontifical Academy for Life and the National Catholic Bioethics Center have determined that vaccines grown in these cell lines do not defy the religion’s doctrine:

Vaccine safety related to remaining DNA

The concern about DNA is that it can cause changes in the vaccine recipient’s DNA. This is unlikely for two reasons:

  • Most of the foreign DNA is destroyed during the process of making the vaccine; the minimal amount that remains (trillionths of a gram) is highly fragmented. Because DNA is fragmented, it cannot possibly create a whole protein.
  • The chance that foreign DNA would incorporate into a region of cellular DNA (i.e. promoter region) is about zero. In fact, if the trace quantities of residual DNA present in vaccines (and other biologicals) could incorporate itself into host DNA behind a promoter region and be stably expressed, studies of gene therapy would have been much more successful.

Vaccine safety related to human proteins

The concern about contamination of vaccines with human proteins seems to be relatively new. Because viruses are purified during vaccine production, it is unlikely that proteins from the human cells used to grow them would survive intact or in quantities sufficient to cause harm.

Resources for parents

Materials in this section are updated as new information and vaccines become available. The Vaccine Education Center staff regularly reviews materials for accuracy.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family's personal health. You should not use it to replace any relationship with a physician or other qualified healthcare professional. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult your physician or, in serious cases, seek immediate assistance from emergency personnel.