A group of students at Creighton University in Nebraska filed suit last week over the Jesuit university's refusal to consider religious exemptions to its COVID-19 student vaccination requirement. Pope Francis and the U.S. Conference of Bishops have both urged people to get vaccinated against COVID-19, but the students say they have objections because the vaccines were developed or tested on cell lines derived from aborted fetal tissue. As Nebraska Medicine, a regional health-care network, explains in a Q and A on its website, "The COVID-19 vaccines do not contain any aborted fetal cells. However, fetal cell lines -- cells grown in a laboratory based on aborted fetal cells collected generations ago -- were used in testing during research and development of the mRNA vaccines, and during production of the Johnson and Johnson vaccine."