Do vaccines contain stem cells?

Monday, December 13, 2021
By Lisa Freedland

While vaccines do not contain stem or fetal cells, many common vaccines are developed by growing viruses in fetal embryo cells. 

Examples include those for treating hepatitis A, rabies and chickenpox. Fetal cells were also used during the testing and development of the Pfizer, Moderna and Johnson & Johnson COVID-19 vaccines.

The fetal cells were initially taken from two fetuses aborted in the early 1960s. However, from the beginning, scientists have duplicated these cells in the lab for use — no cells from aborted fetuses are used.

According to scientists, fetal human cells are used rather than animal cells because viruses "tend to grow better" in human cells. Furthermore, as fetal cells do not divide as much as other types of cells, they can be used for far longer. 

This fact brief is responsive to conversations such as this one.
Between 2020 and 2022, under close editorial supervision, Gigafact contracted a group of freelance writers and editors to test the concepts for fact briefs and provide inputs to our software development process. We call this effort Gigafact Foundry. Over the course of these two years, Gigafact Foundry writers published over 1500 fact briefs in response to claims they found online. Their important work forms the basis of Gigafact formats and editorial guidelines, and is available to the public on Gigafact.org. Readers should be aware that while there is still a lot of relevant information to be found, not all fact briefs produced by Gigafact Foundry reflect Gigafact's current methods and standards for fact briefs. If you come across any that you feel are out of date and need to be looked at with fresh eyes, don't hesitate to contact us at support@gigafact.org.