"Two main human cell strains have been used to develop currently available vaccines, in each case with the original fetal cells in question obtained in the 1960s. The WI-38 cell strain was developed in 1962 in the United States, and the MRC-5 cell strain (also started with fetal lung cells) was developed, using Hayflick's technology, in 1970 at the Medical Research Center in the United Kingdom. It should be noted that Hayflick's methods involved establishing a huge bank of WI-38 and MRC-5 cells that, while not capable of infinitely replicating like immortal cell lines, will serve vaccine production needs for several decades in the future."