Because human embryo cells are used to make a few vaccines, including the chickenpox, rubella, hepatitis A, one version of the rabies, and one version of the COVID-19 vaccines, people have asked whether proteins from these fetal cells are still present in the final vaccine preparations. The quantity of DNA in these vaccines is typically measured in picograms (trillionths of a gram).

Viruses are purified during vaccine production; therefore, it is unlikely that proteins from the human cells used to grow them would survive intact or in quantities sufficient to cause harm.

Reference

Offit PA and Moser CA. Vaccines and Your Child: Separating Fact from Fiction. 2011. Columbia University Press.