"Vaccine manufacturers have few options for viral culture media, for reasons of microbiology and safety. It is not possible to simply replace one cell line with another, because various viruses grow abundantly only in some kinds of cell lines. WI-38 and MRC-5 lines are well described and understood, with experience accumulated via hundreds of millions of vaccinations, important for safety-assessment reasons. The fetal origins of WI-38 and MRC-5 cell lines pose an ethical or moral problem for people who disapprove of abortion. Critically, the two abortions were not conducted for the purpose of harvesting the cells that were transformed into these cell lines. This lack of intention is a key element in breaking the complicity link that could otherwise make use of the vaccines unacceptable. No additional abortions are needed to sustain vaccine manufacture. The cell lines are not the final product, and no human cells are present in the final vaccine formulations."