Vaccines are routinely formulated with aborted human fetal cells known as MRC-5 and WI-38. The CDC openly lists some of the vaccines that use these "human diploid" cells, including Twinrix (Hep A / Hep B), ProQuad (MMRV) and Varivax (Varicella / chicken pox). FDA-published vaccine insert sheets such as this one for Varivax also openly admit to the use of aborted human fetal cell lines such as MRC-5:
The product also contains residual components of MRC-5 cells including DNA and protein and trace quantities of neomycin and bovine calf serum from MRC-5 culture media.
Even this GlaxoSmithKline vaccine insert sheet openly discusses the use of aborted human fetal cells in its Priorix-Tetra vaccine (MMRV):
Each virus strain is separately produced in either chick embryo cells (mumps and measles) or MRC5 human diploid cells (rubella and varicella).