Human Fetal Links with Some Vaccines

Updated: Junio 3, 2008

Some people have asked if some vaccines have components derived from human fetuses.

In fact, some vaccines are grown in cell cultures that were originally obtained from two human fetuses. In addition, the rubella virus used to make rubella vaccine was isolated from a third human fetus. This article describes the origins of these vaccines.

Manufacturing Viral Vaccines

It is far more complex to manufacture biological medications (for example, vaccines, antibodies) than it is to produce chemical medications (for example, penicillin or aspirin). In addition, certain vaccines are more complex to make than others. The bacteria that go into bacterial vaccines can be grown in simple laboratory cultures. In contrast, the growth of viruses requires living cells.

Viruses cannot reproduce on their own. They require a living host in which to grow, such as chicken embryos, and cells from animals that are grown in culture. Vaccine manufacturers currently have few options for viral culture, because of valid pharmaceutical reasons and because of human safety concerns. For example, varicella (chickenpox) virus does not grow well in most cells derived from species other than humans. Also, human cells are preferred because cells derived from animal organs sometimes may carry animal viruses that could harm people.

In the future it may be possible to prepare virus vaccines using molecular tools that do not require growing the virus in living cells. For example, today’s hepatitis B vaccines are made using molecular tools that do not require animal cells at all. It is not possible to prepare most virus vaccines using these methods now, however.

Human Fetal Diploid Cells

Human diploid cells are batches of human cells that are grown in a laboratory. Unlike cancer cells, they have the same number of chromosomes as normal human cells.

Certain diploid cell strains are valuable in vaccine manufacture because these cells can be used for a very long period of time in the laboratory and are a reliable means by which many viruses that infect humans can be successfully and easily grown. Vaccines prepared in human diploid cells have proven to be very safe over the past several decades.

Two different strains of human diploid cell cultures made from fetuses have been used extensively for vaccine production for decades. One was developed in the United States in 1961 (called WI-38) and the other in the United Kingdom in 1966 (called MRC-5).

WI-38 came from lung cells from a female fetus of 3-months gestation and MRC-5 was developed from lung cells from a 14-week-old male fetus. Both fetuses were intentionally aborted, but neither was aborted for the purpose of obtaining diploid cells.123. The fetal tissues that eventually became WI-38 and the MRC-5 cell cultures were removed from fetuses that were dead. The cellular biologists who made the cell cultures did not induce the abortions.

These two cell strains have been growing under laboratory conditions for more than 35 years. The cells are merely the biological system in which the viruses are grown. These cell strains do not and cannot form a complete organism and do not constitute a potential human being. The cells reproduce themselves, so there is no need to abort additional fetuses to sustain the culture supply. Viruses are collected from the diploid cell cultures and then processed further to produce the vaccine itself.

The WI-38 and MRC-5 cell cultures have been used to prepare hundreds of millions of doses of vaccines, preventing millions of cases of rubella, hepatitis A, varicella and rabies. In the United States, only one of these diseases can be prevented with an FDA-licensed vaccine not grown in human diploid cells. This is the RabAvert brand of rabies vaccine manufactured by Chiron Corporation.4

Some of the vaccines that are produced in human diploid cells might now be able to be prepared in alternative types of cell cultures. Some of these cell cultures were not available or were not considered suitable for use in vaccines when the original vaccines were developed. However, there is no guarantee that vaccines grown in these alternative cell lines would be as safe and effective as currently licensed vaccines and development is likely to be extremely costly. Thus, there is little incentive for vaccine manufacturers to develop and test new vaccines when an existing licensed vaccine is known to be both safe and effective.

Rubella Vaccine Virus

Rubella virus causes a mild illness in most children, but may severely damage the developing fetus when a pregnant woman becomes infected. The virus that led to the only rubella vaccine available in the United States and that is widely used overseas (Meruvax II, Merck) came from tissues obtained at the time of an abortion performed on a rubella virus-infected mother.5 The abortion was not conducted in order to isolate the virus, but rather because the mother and the fetus were infected with wild rubella virus that posed a risk of major birth defects.67

Since that wild strain of rubella virus (known as RA27/3) was isolated, it has been grown in human fetal diploid cells. There is no need to obtain additional cells from aborted fetuses to sustain the supply of attenuated rubella viruses used to manufacture additional batches of rubella vaccine for the future.

During the development of the present rubella vaccine, cells from animals other than humans were also studied for vaccine manufacture but these proved to be less safe and/or less effective than the RA27/3 vaccine grown in WI-38 cells.

Before widespread use of the rubella vaccine, there were hundreds of thousands of cases of rubella in the United States and more than 800 cases of congenital rubella per year.8. As a consequence of the rubella epidemic of 1963-1964 it is estimated that there were 20,000 infants born with congenital defects, 6,250 spontaneous abortions and 5,000 induced abortions.9 In 2001, CDC reported just 3 babies born with congenital rubella syndrome.10

Thus, the RA27/3 rubella vaccine has prevented many thousands of spontaneous and induced abortions by protecting pregnant women from infection.9. See this article (PDF 479 k)


Some vaccine components have been derived from human fetuses. The abortions were not conducted for the purpose of vaccine discovery or vaccine production. Additional abortions are not needed for the production of these vaccines. In the case of rubella vaccine, abortions are prevented by the use of the vaccine.

A recent report from the Pontifical Academy for Life at the Vatican encourages pharmaceutical companies to seek alternatives to the development of vaccines linked with human fetuses, given the Catholic Church’s objections to cooperating with abortion.11 The report also points out that in the absence of an alternative, these vaccines may be utilized “to avoid a serious risk not only for one’s own children but also, and more specifically, for the health conditions of the population as a whole – especially for pregnant women.” The Vatican Academy also noted that “the parents who did not accept the vaccination of their own children become responsible for the malformations [due to rubella infection] in question.”


  • 1. Hayflick L, Moorhead PS (1961). The serial cultivation of human diploid cell strains. Experimental Cell Research 25:585-621.
  • 2. Hayflick L (1965). The limited in vitro lifetime of human diploid cell strains. Experimental Cell Research 37:614-36.
  • 3. Jacobs JP, Jones CM, Baille JP (1970). Characteristics of a human diploid cell designated MRC-5. Nature 227:168-70.
  • 4. Grabenstein JD. Moral Considerations with Certain Viral Vaccines. Christianity & Pharmacy 1999; 2(2):3-6
  • 5. Perkins FT (1985). Licensed vaccines. Review of Infectious Diseases 7(Supplement 1):S73-6.
  • 6. Plotkin SA, Farquhar JD, Katz M, Buser F (1968). Attenuation of RA27/3 rubella virus in WI 38 human diploid cells. American Journal of Diseases of Children 118:178-85.
  • 7. Hayflick L, Plotkin S, Stevenson RE (1987). History of the acceptance of human diploid cell strains as substrates for human virus vaccine manufacture. Developmental Biology Standards 68:9-17.
  • 8. CDC. Achievements in Public Health, 1900-1999: Impact of vaccines universally recommended for children – United States, 1900-1998. MMWR 1999; 48:243-248.
  • 9. a. b. Plotkin SA, Reef S. Rubella Vaccine [Chapter 26]. In: Plotkin SA, Orenstein WA (Eds). Vaccines (4th Edition). Philadelphia, PA: W.B. Saunders Company, 2004.
  • 10. CDC. Summary of notifiable diseases – United States, 2001. MMWR 2003; 50(53): 3.
  • 11. Pontificial Academy of Life. Moral Reflections On Vaccines Prepared From Cells Derived From Aborted Human Foetuses. Vatican City: 2005 (English translation from the Italian). See also the response from the National Catholic Bioethics Center.

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