"Neither does it seem that use of these vaccines will encourage future abortions. Regrettably, the cell lines that gave rise to MRC-5 and WI-38 began with tissue taken from aborted human beings, but these immoral actions were one-time events. Since their first beginnings, the cells used for these lines have continued to duplicate and grow in culture. There is little incentive to begin new human cell lines when these are well established and their various scientific properties well understood."