"In 1972, a female child was aborted in the Netherlands, and cells from her kidneys were extracted and developed into the cell line now known as "HEK293." "HEK" stands for "Human Embryonic Kidney." Cells from the HEK293 line have been commonly used in biologic research since the late 70s. The vaccinations produced by Pfizer and Moderna did not use HEK293 in their design, development, or production, but did use cells from the line in a confirmatory test, said the bishops. "While neither vaccine is completely free from any connection to morally compromised cell lines, in this case the connection is very remote from the initial evil of the abortion," said the bishops. Conversely, the vaccine produced by AstraZeneca "should be avoided if there are alternatives available," said the bishops, as this vaccine is "more morally compromised." "The HEK293 cell line was used in the design, development, and production stages of that vaccine, as well as for confirmatory testing," said Rhoades and Naumann. The two compared the AstraZeneca vaccine to the current rubella vaccine, which also was reliant on "morally compromised cell lines." In the case of the rubella (German measles) vaccine, explained the bishops, the risk posed to an unborn child and the community at large by the illness outweigh the morality concerns related to the development of the vaccine. "In such a situation, parents are justified in having their children vaccinated against rubella, not only to avoid the effects of rubella on their children, but, secondarily and just as importantly, to prevent their children from becoming carriers of rubella, as the spread of rubella can lead to the infection of vulnerable pregnant women, thereby endangering their lives and the lives of their unborn children," said the bishops. Rhoades and Naumann acknowledged that while Catholics should avoid the AstraZeneca vaccine in preference for one of the other two, it may not be possible for someone to do this without putting society at risk from the coronavirus. If this were to happen, a Catholic would be permitted to receive that vaccine."