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Gina Harper, clinical coordinator with pharmacy, measures out the exact amount of the COVID-19 vaccine for a dose before it is administered to health care providers at UC Health Poudre Valley Hospital. There were 20 people from northern Colorado health care facilities vaccinated on Dec. 14, 2020. (Helen H. Richardson/The Denver Post, Pool)

Catholic bishops from Colorado’s three dioceses warned parishioners about moral questions behind the new COVID-19 vaccines in an open letter this week, noting that vaccine producers may have used aborted fetal cells in creating their vaccines or during lab tests. 

The letter from the bishops in Denver, Colorado Springs and Pueblo comes as the first doses of the vaccine arrived in Colorado for health care workers. 

Vaccines created by Pfizer and Moderna, the first two vaccines coming on the market for the public, are “morally acceptable” because neither company used “fetal cell lines from an aborted baby” during production, the letter states. But the companies both relied on those cells during lab tests, the bishops said.


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“In our current circumstances, when better options are not available, the use of the Pfizer and Moderna vaccines remains a morally valid option,” the bishops wrote. “On the other hand, vaccines such as AstraZeneca-Oxford use aborted fetal lines in design, development, production and testing, and therefore are not a morally valid option because better options are available.”

The point of the letter was to “affirm that the use of some COVID-19 vaccines is morally acceptable under certain circumstances,” it says. 

The letter was signed by Archbishop Samuel J. Aquila of Denver, Pueblo Bishop Stephen J. Berg, Colorado Springs Bishop Michael J. Sheridan and Auxiliary Bishop of Denver Jorge Rodriguez. 

Denver Archbishop Samuel Aquila. (Photo provided by Brandon Young, Archdiocese of Denver)

Vaccines work by giving the immune system a sparring partner that looks like the wild virus, so the immune system can practice and perfect its response. In most vaccines this is done by injecting people with either an inactivated form of the virus or another harmless virus that is genetically modified. The AstraZeneca-Oxford vaccine uses an adenovirus, which is harmless to humans and causes a common cold in chimpanzees, that has been modified to have the coronavirus’s distinctive spike proteins on the outside.

Growing enough of this virus to put into the vaccine requires cell cultures, which often use cell lines that were originally derived from aborted fetuses. Production of the AstraZeneca-Oxford vaccine uses cells that are clones of a cell line that came from the kidney of an aborted fetus in 1973.

“What’s important for the public to know even if they are opposed to the use of fetal cells for therapies, these medicines that are being made and vaccines do not contain any aspect of the cells in them,” Dr. Deepak Srivastava, the former president of the International Society for Stem Cell Research, told The Associated Press last month. “The cells are used as factories for production.”

The Pfizer and Moderna vaccines use a new platform involving messenger RNA — little bits of genetic material that prompt the body’s own cells to manufacture the coronavirus spike protein to serve as a test dummy. This type of vaccine doesn’t require cell culture for production.

The letter, published on the website “Denver Catholic,” notes that Catholics have a duty to use vaccines that respect human life, when available. The church called the vaccines for COVID-19 “necessary and urgent,” but said that “a good end cannot justify evil means.” 

Vaccine production that uses cell lines from aborted fetuses “offends the dignity of the preborn aborted baby and his or her family, as well as the dignity of the medical vocations of doctors and scientists,” the church leaders wrote.

“In the case of a global pandemic, the Catholic commitment to promoting the common good includes considering the health and safety of others,” they wrote. However, they noted that the government should not impose the COVID-19 vaccine on its citizens.

Neither federal or state government leaders have said they would attempt to force people to take the vaccine.

The religious concerns about some of the coronavirus vaccines under development are not confined to Colorado. Church leaders across the country and around the world have also raised similar points.

And Dr. Eric France, the chief medical officer of the Colorado Department of Public Health and Environment, said debate over the use of cell lines derived from aborted fetuses also predate the COVID-19 vaccines, as do other religious concerns about vaccine production. In the past, France said, numerous faith leaders have spoken in favor of vaccination.

“Their comments and conclusions have been that the propensity of good created by the vaccine favors the vaccine use,” France said.

The AstraZeneca-Oxford vaccine, once the frontrunner among COVID-19 vaccine candidates, is not expected to be approved until at least February. By then, it is unclear how many other vaccines will have also been approved or how much supply of the Pfizer and Moderna vaccines there will be.

Colorado does not expect to begin vaccinating high-risk members of the general public until spring, and healthy members of the general public will likely become eligible for the shot in summer.

France said it is too early to say whether people will be able to choose which company’s vaccine they get when their opportunity comes up.

“I imagine if there’s a big supply there will be choice available,” he said. “If there isn’t a choice, it may be you get what you get or you choose not to get vaccinated since vaccination ultimately is an individual decision.”

John Ingold

John Ingold is a co-founder of The Colorado Sun and a reporter currently specializing in health care coverage. Born and raised in Colorado Springs, John spent 18 years working at The Denver Post. Prior to that, he held internships at the Rocky Ford Daily Gazette, the Colorado Springs...

Jennifer Brown

Jen is a co-founder and reporter at The Sun, where she writes about mental health, child welfare and social justice issues. Her first journalism job was at The Hungry Horse News in her home state of...