"Another reason WI-38 has become so ubiquitous is that a quirk of the American legal system at the time of its discovery: it wasn’t possible to patent living things. This means their use was never restricted, and scientists around the world were able to share them freely with colleagues. Though there are hundreds of cell lines available in the United States, WI-38 makes up the majority of the cells used, together with just one other. “MRC-5” cells, named after the initials of the Medical Research Council where they were collected, were obtained from the lungs of another three-month-old foetus. This time the abortion happened in England in 1966 for “psychiatric reasons”. WI-38 was fundamental for the development of vaccines against polio, measles, mumps, rubella, varicella zoster (chicken pox), herpes zoster, adenovirus, rabies and Hepatitis A, as well as in the production of many early vaccines. Today it's still used to make the rubella vaccine – part of Merck's measles, mumps and rubella (MMR) jab – and Teva's adenovirus vaccine for the US military."