Father Thomas Burg of St. Joseph’s Seminary, is a moral theologian and specialist in bioethical issues.  He offers counsel on the ethical issues involved in taking the Coronavirus vaccine.  His judgment is that the Pfizer and Moderna vaccines are not morally problematic:
 
“The rapid development of Covid vaccines raises the perennial question of whether it is licit to receive vaccines that, in their production, have relied to some degree on human cells historically derived from aborted fetuses.
 
These cell lines were derived many years ago from post-abortion fetal tissue. Examples:  HEK-293, MRC-5 and WR-38 were generated from abortions that occurred in the 1960s and 1970s.  HEK cells, for example, are kidney cells from the aborted fetus. They are routinely used in research today--almost without thought. 
 
With regard to the two leading candidate vaccines (one produced by Pfizer, the other by Moderna), there is much good news. Given the technology used, there is no need for a culture medium, no need for live cell cultures, etc.  Instead of using live or diminished Covid virus to generate an immune response, these vaccines rely on coronavirus's outer spike proteins, which are what antibodies use to recognize the virus.  Researchers use the genetic code that coronavirus uses to produce spike proteins. They employ molecules called RNA to transport this synthetically made genetic information into our cells. When injected into a patient, the RNA enters healthy cells where it helps orchestrate the production of coronavirus spike proteins. Once in the system, this prompts the body to create antibodies. This same technology is currently used in cancer therapy to genetically target specific cancers.  There is no use of any fetal tissue in the actual process or production of the vaccine itself.”
 
The bottom line is Catholics should feel free to take the vaccine when it becomes available.