In late August, a group of NYPD officers sued New York City for rejecting their requests for religious exemptions to the city’s municipal employee COVID-19 vaccine mandate. A similar lawsuit by students at Creighton University in Nebraska was recently dismissed. Earlier this year, Supreme Court Justice Clarence Thomas expressed support for religious exemptions to COVID-19 vaccine mandates because the vaccines were developed using cells from what the plaintiffs, quoted in Thomas’s dissent, described as “aborted children.” The cells at the heart of this controversy are largely unknown to the general population, but they are an indispensable part of modern medical research and crucial to the development of some of the most common medications on the market. 

HEK293: The cells that drive biomedical research

Human embryonic kidney 293 (HEK293) cells are one of the most widely used cell lines in research. Used in everything from cancer research and the development of new drugs to safety tests of chemicals, these cells are easy to manipulate and are immortal, meaning they can be grown and replicated in a lab indefinitely. HEK293 cells were collected in the 1970s from fetal tissue, either from an elective abortion or a miscarriage. The cells have been replicated many thousands of times, and several other useful cell lines have been derived from the original HEK293 cells. Both the Pfizer and Moderna COVID-19 vaccines were developed in HEK293 cells, while Johnson & Johnson’s vaccine development used a different fetal cell line called PER.C6. 

Use in medical research and drug development

In labs around the world, scientists are conducting innovative, lifesaving research using HEK293 cells. It’s almost guaranteed that anyone reading this article has, at some point in their life, taken a medication developed or tested in HEK293 cells, including most over-the-counter antacid, pain, allergy, and cold medications and several widely used vaccines. Monoclonal antibody treatments that prevented severe illness and death in hundreds of thousands of COVID-19 patients, including former President Donald Trump, were developed in HEK293 cells. Remdesivir, an FDA-approved COVID-19 treatment, was tested in the cells, as were ivermectin and hydroxychloroquine, two drugs that made headlines when vaccine skeptics embraced them as COVID-19 treatments without evidence. 

Religious objections to fetal-derived cell lines

Some religious groups have argued that the use of fetal cells in the development of COVID-19 vaccines is grounds for religious exemptions from vaccine mandates. However, this objection rarely extends to the dozens of drugs in every medicine cabinet that were developed and tested in the same fetal-tissue-derived cell lines as COVID-19 vaccines. That lack of consistency calls into question whether these beliefs are sincerely held, a standard that must be met to obtain religious exemptions. 

Although there is disagreement among religious adherents, no major religion objects to the use of COVID-19 vaccines, and most faiths encourage vaccination. In 2020, shortly after the first COVID-19 vaccine became available, Pope Francis approved an official statement declaring COVID-19 vaccines developed using fetal cell lines morally acceptable. The vaccines are considered halal (permissible) under Islamic law and are encouraged by many Islamic leaders and scholars. 

COVID-19 vaccine development is not exceptional for having used HEK293 cells. What is exceptional is the level of scrutiny and backlash leveled at COVID-19 vaccines—and these vaccines alone—for being developed in the ubiquitous cells that have powered medical advancement for decades.