By Helen Petousis Harris 26/08/2020

When science meets ethics and morality.

Vaccines are biological products and will have be exposed to various organic and inorganic products during their manufacture, depending on vaccine type. This includes exposure to human cells. Research that informs vaccine development will certainly have relied on such products along the way. Some people have faith, morality or safety-based concerns about the use products sourced from animals, such as gelatin. Animal products used during the manufacturing process, if still present in the finished vaccine, are only present in minute (trace) amounts and are not ‘vaccine ingredients’ per se. If you have ever had a medical intervention of pretty much any kind you will probably have ultimately benefited from the use of animal cells or product. But what about human cells?

No COVID-19 vaccines are not made from aborted fetuses! Also (other than the TB vaccine), there are no actual cells in vaccines. However, there are things called human cell lines that have been derived from several fetuses, embryos, and cancer. Most many decades ago. This is because scientists need to study human diseases in human cells. Also, viruses need cells in order to replicate, they cannot do this without hijacking the machinery of a cell to make more of themselves. In the case of some viruses only a human cell will do, they refuse to replicate in alternatives. Over time scientists have found other approaches for some vaccines and other research that avoids human cell lines, but not all.

The pressure is on for COVID-19 vaccines.

Right now there is enormous pressure on scientists to develop and produce safe and effective COVID-19 vaccines. To be honest there is no time to start searching for alternative cells lines that reliably allow the study of COVID-19 disease, or in the development of vaccines. The world is demanding the availability of vaccines yesterday, you can’t necessarily always have it both ways.

Human cell lines

In order to conduct research on human diseases human cells are required and those cells need to possess certain properties. Also, some viruses will only grow in human cells, such as rubella virus.

This means that stocks of human cells are needed. The cells must be sterile and free from potential harmful agents. They must also be immortal, able to divide and divide for ever. Normal cells only divide for a while then they stop and die. You start with a few cells from the freezer and nurture them until they are billions, all identical. The ancestors of some of these cells are over half a century old and have ended up in laboratories all over the world. Many medical breakthroughs have relied on these cells.

Mainly in the 1960’s and 70’s some human cell lines were established from fetal and embryonic cells which are able to divide virtually indefinitely. These were obtained from several electively aborted pregnancies. Babies are not being aborted in order to produce vaccines. The cells used now are not the originally harvested cells, they are descendants of those cells. Perpetual human cell lines from decades ago are used to both study diseases and to grow several viruses for vaccine use, they are not part of the final formulation. One example is the HEK-293 cell line which was isolated from a human embryo electively aborted in the Netherlands in 1973. Each cell line has its own history. However, other than the TB vaccine, vaccines do not actually contain cells.

The other source of human cell lines are from cancer patients where the unchecked division of cancer cells has rendered them immortal, an example is HeLa cell line derived from Henrietta Lacks who did from cervical cancer in 1951. This cell line comes with its own ethical considerations as Henrietta was not aware her cells were used.

All these cell lines are characterised and named.

COVID-19 vaccines and human cell lines

While some of the approaches to vaccine manufacture do not require the use of cells of any kind (such as the RNA vaccines), others do. The viral vector vaccines do require the use of cells. The viral vector is a well characterised virus such as an adenovirus that has had a coronavirus gene inserted. The combination goes through its life cycle or is ‘grown’ in cells. These calls can pump out massive amounts of the viral protein (or the viral vector vaccine) that can then be purified and used in the final formulation. Many vaccines are grown in non-human cells, such as the HPV and hepatitis B vaccines, which use bakers yeast or an insect cell line. However, when a new virus that affects humans emerges and the scientists are under massive time pressures, using human cell lines is a pragmatic choice. The system needs to look as human as possible to have the best chance of success.

There are several COVID-19 vaccine approaches in development that use a human cell line to grow the vaccine, this includes the Oxford/AstraZeneca viral vector vaccine These cell lines have been used safely and effectively for decades, are very well characterised, and licensed for use in the production of human medicines. The nucleic acid vaccines (RNA vaccines) are not made in cell lines at all.

Moral and ethical issues

The use of these cells, and in fact any animal cells, raises a whole host of moral and ethical considerations for a variety of people for different reasons. Most recently this conversation has arisen around COVID-19 vaccines. With respect to cells derived from an abortion perhaps there is the sense that by using or accepting them one might be in some way complicit in the actual abortion.

The position of The Vatican is that where there is no alternative vaccine, the use of vaccines developed from an historical fetal cell line should not be misinterpreted as approving their production, marketing and use, but consider use of the vaccine as morally justified to avoid a serious risk, not only for one’s own children but for the health of the whole population. The choice to vaccinated outweighs the legitimate concerns about the origins of the vaccine. [See here and here for Vatican views]

We cannot avoid these cell lines if we are to have COVID-19 vaccines anytime soon. Even the RNA vaccines, which do not require cells to make, will have benefited from research that utilised human cell lines.



For more information about animal products and vaccines as well as different positions on these see the factsheet from the Immunisation Advisory Centre