Embryonic Cell Lines: Why Some Religious Groups Have Singled Out the Johnson & Johnson Vaccine

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As of the time I’m writing this in March, 2021, there are three approved vaccines against SARS-CoV2 (the virus that causes COVID19) in the United States. If you have been reading The Pulse, you know that all three vaccines are extremely effective stimulating immunity against the first version of the virus that caused COVID19 throughout the world (we’ll call it the wild type) and against what’s called the B.1.1.7 variant (the “UK” variant) of the virus and also appears to provide pretty good protection against what have emerged as new American variants, notably the B.1.427/429 (California), and okay protection even against variant B.1.351 (South African). From this blog, you also may know that all three vaccines are very safe, including for pregnant women, that the benefits of getting vaccinated, with the Pfizer-BioNTech, Moderna, or the Johnson and Johnson vaccine (Janssen vaccine) against SARS-CoV2 far exceeds any risks.

But you may have heard a new angle in the news, regarding the Johnson and Johnson vaccine bothering certain religious leaders, notably some bishops of Roman Catholic Church, because a line of cells from human embryos is used in the manufacturing process. In the United States, this played out in early March with the Archdioceses of New Orleans and Catholic leaders in St. Louis suggesting that their followers should avoid the Johnson and Johnson vaccine. In response to this, Pope Francis issued a statement reiterating a recommendation released months earlier saying, “it is morally acceptable to receive COVID-19 vaccines that have used cell lines from aborted fetuses in their research and production process” and that had continued as follows: “All vaccines recognized as clinically safe and effective can be used in good conscience.” Mentioning the Johnson and Johnson vaccine specifically, the more recent Vatican statement was to the effect that Catholics should get vaccinated, no matter what, as early as possible, but that, if given the choice between different vaccines, that they should opt for one of the mRNA vaccines (Pfizer-BionTech, Moderna) over the Johnson and Johnson.

The Pope’s statement overrules the move by local bishops’ desire for Catholics to avoid the Johnson and Johnson vaccine at all costs, but potentially it can still be harmful, because it can lead to a good number of people avoiding vaccination altogether, and cause others to reject the particular COVID19 vaccine that might be best suited for them for a combination of reasons. Although there also may be leaders of other religions with outlying opinions about the Johnson and Johnson vaccine, mainstream religious groups tend to place healing and prevention of illness against other concerns. In Judaism, for example, the phenomenon of embryonic cells involved in the research and production of the Johnson and Johnson vaccine is not an issue at all, as the emphasis is on promoting the health of people who are already born.

Now, the Johnson and Johnson vaccine carries many advantages. As of the time that I am writing this (early March), it appears that who receives which vaccine and which vaccines go to which vaccinating facilities will depend mostly on logistical factors. With respect to the Johnson and Johnson vaccine, the requirement of standard refrigerator temperatures, rather than deep freezer temperatures, for storing and transporting the vaccine, plus the fact that it is a one-dose regimen are very favorable. There are many regions where it will now be a lot easier to vaccinate large amounts of people with the Johnson and Johnson vaccine than it would have been with the two mRNA vaccines. On top of that, even in major metropolitan areas of North America, where it is practical to store large numbers of mRNA vaccine doses in deep freezers, polling data suggest that the Johnson and Johnson vaccine is destined to be more favorable in the eyes of many people compared with the mRNA vaccines. The reason for this is simple; people would rather have one shot than two. With no need to get people to return for a second shot, the Johnson and Johnson vaccine avoids the potential problem of some people not returning for a needed second shot. While such personal preference and logistical reasons in favor of the Johnson and Johnson vaccine are supported by solid evidence, there also are some medical possibilities of a more hypothetical nature, namely that the Johnson and Johnson vaccine may turn out to be better for people in certain medical situations, but before going into that let’s unpack the biology a bit.

As opposed to the Pfizer/BioNTech and Moderna vaccines, whose business end is a strip of mRNA enclosed within what’s called a lipid nanoparticle, the Johnson and Johnson vaccine has a strip of DNA as its business end. This DNA is enclosed within a virus called adenovirus-26. As opposed to lipid nanoparticles, which are created in a chemical engineering process, adenoviruses must be grown in cells and that’s the part where embryonic cell line comes in. The cells used to grow the adenovirus-26 are not capable of developing into a human embryo. But they are descendants of cells from embryos that were cold preserved about 40 years ago and then used to create a line of cells for research purposes. In contrast, because the lipid nanoparticles are not grown in the biological sense as the adenovirus-26, when it comes to the mRNA vaccines, embryonic cell lines were used only in testing during the research part of the process, but not during the industrial process of making the vaccines. Despite the use of the embryonic cell line to grow the adenovirus-26, there are none of these cells in the actual Johnson and Johnson vaccine (the cells are filtered out in the vaccine production process), which is why the Vatican seems to be generally okay with it. But the very same biology may relate to why the Johnson and Johnson vaccine seems to work as a one dose regimen and why this may be desirable for certain people, if there is a choice between vaccines.

Known as nucleic acid vaccines (because the term nucleic acid encompasses both RNA and DNA), all three COVID-19 vaccines approved for emergency use in the United States carry instructions for cells to make the spike protein, that normally sticks out from the surface of the SARS-CoV2 virus. Scientists hypothesis various reasons why the generation of lasting, strong  immunity requires two doses of the mRNA vaccines, but just one dose of Johnson and Johnson DNA vaccine (whereas the AstraZeneca/Oxford vaccine also is a DNA vaccine yet has been studied as a two-regimen, the clinical trial of this two dose regimen was somewhat botched, so we’re not talking about AstraZeneca right now). One possible explanation —which needs to be tested in scientific studies, but it makes sense— is that a shot of the Johnson and Johnson vaccine may cause cells in the shoulder, including antigen presenting cells in the injection site and in lymph nodes in the arm pits that drain the site, to make spike protein for a more extended period of time than the mRNA vaccines do, because mRNA entering cells has a very short life span (measured in hours), whereas DNA delivered in by an adenovirus enters the nucleus of the cell and forms what’s called an episome. An episome is a circle of DNA that remains separate from the cell’s chromosomes, but it stays around much, much longer than a strip of RNA. While staying around as an episome, the DNA of the Johnson and Johnson is transcribed into mRNA, over and over, so, in a certain sense, it’s like getting a shot of mRNA vaccine day after day.

But whatever the reason for the Johnson and Johnson being effective after a single dose, the fact that the immune system sees the carrying agent, the adenovirus-26, to which most people have never been exposed before, means that the immune response to this carrier is going to be fairly mild. In contrast, while the mRNA vaccines use as carriers for their mRNA lipid nanoparticles, which are not thought to provoke the immune system much, the second time you receive these particles, the immune system is being exposed to something it has seen a few weeks before. This may very well be the reason for some strong reactions that people experience after the second dose, suggesting, in turn, that Johnson and Johnson, may actually turn out —after more research is conducted— to go easier on people who have certain medical conditions.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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