https://slate.com/technology/2017/03/the-woman-whose-aborted-fetus-helped-create-the-rubella-vaccine.html

https://en.wikipedia.org/wiki/Use_of_fetal_tissue_in_vaccine_development

What is going on? Why did no one tell me this? I thought I had broad general knowledge but have never encountered this before.

It fits into the other scary medical experimentation of the post WW2 decades.