On December 14, the U.S. Catholic Conference of Bishops issued a statement on the new COVID-19 vaccines. In their statement, the bishops address the moral concerns raised by the fact that the three vaccines that appear to be ready for distribution in the United States all have some connection to cell lines that originated with tissue taken from abortions. 
With regard to the Pfizer and Moderna vaccines, they concluded: “In view of the gravity of the current pandemic and the lack of availability of alternative vaccines, the reasons to accept the new COVID-19 vaccines from Pfizer and Moderna are sufficiently serious to justify their use, despite their remote connection to morally compromised cell lines. 
“Receiving one of the COVID-19 vaccines 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.” 
With regard to the AstraZeneca vaccine, the bishops found it to be “more morally compromised” and consequently concluded that this vaccine “should be avoided” if there are alternatives available. “It may turn out, however, that one does not really have a choice of vaccine, at least, not without a lengthy delay in immunization that may have serious consequences for one’s health and the health of others,” the bishop chairmen stated. “In such a case … it would be permissible to accept the AstraZeneca vaccine.”
At the same time, the bishops also warned that Catholics “must be on guard so that the new COVID-19 vaccines do not desensitize us or weaken our determination to oppose the evil of abortion itself and the subsequent use of fetal cells in research.”