 Also, producing a safe vaccine for many diseases requires the use of these cell strains.The Catholic Church, which opposes abortion, has stated that vaccination should not be refused on moral grounds in cases where the public health benefits of vaccination may outweigh the use of aborted fetal tissue to develop some vaccines, when an alternative vaccine created from cell lines that are not morally problematic are not available.Immortalised cell lines are an important research tool offering a stable medium for experiments.