The new Johnson & Johnson COVID-19 vaccine may offer the best prospect for protecting as many Americans as possible, as quickly as possible, but some U.S. faith leaders say they have moral concerns about its development.Unlike the Pfizer-BioNTech and Moderna vaccines, the Johnson & Johnson vaccine was produced in part through the use of cell lines derived from an aborted human fetus. In a statement released this week, leaders of the U.S. Conference of Catholic Bishops said that this feature of the vaccine raises questions about its permissibility."If one has the ability to choose a vaccine, Pfizer or Moderna's vaccines should be chosen over Johnson & Johnson's," say Archbishop Joseph F. Naumann of Kansas City, Kan., and Bishop Kevin C. Rhoades of Fort Wayne-South Bend, Ind. Naumann chairs the USCCB's Committee on Pro-Life Activities, and Rhoades chairs the USCCB's Committee on Doctrine.The bishops stop well short of telling U.S. Catholics to avoid the Johnson & Johnson vaccine altogether, a position also taken by other faith leaders known for their strong opposition to abortion."We should oppose authorizing or funding research rooted in the taking of innocent human life," says Russell Moore, president of the Ethics & Religious Liberty Commission of the Southern Baptist Convention."That does not mean, though," Moore tells NPR, "that people must shun medical treatments that can save lives because they were discovered through means of which we would not necessarily approve."In practice, Americans who are able to get a COVID-19 vaccine generally have no choice about which one they receive. Vaccination centers are generally able to offer only those vaccines to which they have access. Given those circumstances, the faith leaders' advice that people should feel free to use the Johnson & Johnson vaccine if alternatives are not available may be the most important part of their counsel.In their statement on the advisability of the various COVID-19 vaccines, the U.S. bishops cite a judgment from the Vatican's Congregation for the Doctrine of the Faith."When ethically irreproachable COVID-19 vaccines are not available," the Vatican office said, "it is morally acceptable to receive COVID-19 vaccines that have used cell lines from aborted fetuses in their research and production process."The Johnson & Johnson vaccine was developed with the use of PER.C6, a fetal cell line that originated in an 18-week-old fetus aborted in 1985. According to a June 2020 article in Science, human fetal cells can be used as "miniature 'factories' to generate vast quantities of adenoviruses ... that are used as vehicles to ferry genes from the novel coronavirus that causes COVID-19."The Pfizer and Moderna vaccines also make use of human fetal cells, but only during testing of the vaccines' efficacy, a fact that makes them acceptable, according to a lengthy statement from the U.S. bishops issued in December."While neither vaccine is completely free from any connection to morally compromised cell lines," the bishops said, "in this case the connection is very remote from the initial evil of the abortion."One U.S. Catholic leader, Bishop Joseph Strickland of Tyler, Texas, has said he opposes the use of any COVID-19 vaccine with any connection to aborted human fetuses, no matter how remote, but his extreme position on the issue is an exception among Catholic leaders. Pope Francis and Pope Emeritus Benedict XVI both received COVID-19 vaccines as soon as they were available.In their statement on ethical considerations around the use of COVID-19 vaccines, the U.S. bishops said a vaccination "ought to be understood as an act of charity toward the other members of our community. In this way, being vaccinated safely against COVID-19 should be considered an act of love of our neighbor and part of our moral responsibility for the common good."The Johnson & Johnson vaccine has just now become available in the United States, and Catholic hospitals and other church-affiliated health care institutions are still grappling with the implications of the bishops' advice to avoid the vaccine if possible.At least one Catholic hospital has already faced that challenge. Holy Cross Hospital in Silver Spring, Md., received 500 doses of the Johnson & Johnson vaccine this week and is planning to administer them as soon as possible, despite the vaccine's connection to fetal cell lines."It is a safe vaccine," says the Rev. Kirtley Yearwood, the hospital's chief mission officer. "It has a wonderful record as far as being able to prevent serious illness and hospitalization. Those are very remote cell lines. It's not a primary concern when you have the greater issue of saving lives." Copyright 2021 NPR. To see more, visit https://www.npr.org.