The MMR vaccine contains tissue from aborted fetuses, listed openly in its own ingredients
By The Conspiratory EditorsSeptember 2, 2026
Where the evidence lands: ContradictedThat the MMR vaccine contains material from aborted fetuses, such that anyone receiving it is injected with fetal tissue, and that this is documented in the vaccine's own ingredient list.
Contradicted. This is one of the most precisely constructed false claims in the corpus, and taking it apart requires conceding most of it. In an X post on 25 August 2026 the US health secretary wrote that the rubella virus in MMR-II is grown on a cultured cell line composed of lung tissue from an aborted three-month-old female embryo, that this line is listed as WI-38 human diploid lung fibroblasts in the ingredients, and that portions of those cells end up in each vial. The first two points are accurate and the ingredient listing is real. The last is not: the attenuated virus is extracted from the culture and purified, and no trace of the WI-38 cells remains in the finished vaccine. Snopes rated the claim false. The verdict here applies to that single clause about what is in the vial, not to the history of the cell line, which is real and is a fair subject for moral argument. What this file rates is the substitution of a false empirical claim for an ethical question that can actually be answered.
Believed by: People with a sincere moral objection to abortion who want to know what they are consenting to, which is a reasonable thing to want to know. The claim travels because it appears to answer that question with a document, and because the part of it that is checkable checks out
The full story
Four clauses right, one wrong, and the wrong one is the point
On 25 August 2026, replying on X to a governor who had accused him of spreading vaccine conspiracy theories, the US health secretary set out his claim with unusual precision. The rubella virus in MMR-II, he wrote, is grown on a cultured cell line composed of lung tissue from an aborted three-month-old female embryo; that line is listed as “WI-38 human diploid lung fibroblasts” in the ingredients of MMR-II; and portions of these cells end up in each vial.
Take those in order. The rubella component is grown using WI-38. WI-38 was isolated from the lung tissue of a foetus of about three months, aborted legally in Sweden in 1962. WI-38 is named in the ingredient listing. Anyone who checked those three things found them true.
The fourth is false. The virus is grown in the culture and then extracted and purified, and that purification removes the cells. No trace of WI-38 appears in the finished vaccine. Snopes rated the claim false on exactly that basis.
Compare the earlier version. At a town hall in April 2025 the same speaker said the vaccine “contains a lot of aborted fetus debris”, which is emotive, vague and easy to dismiss. The 2026 version is harder to dismiss precisely because it is mostly correct. The claim did not get louder over sixteen months. It got more accurate, in every part except the one that matters.
Grown in is not made of
The whole thing turns on a distinction that is obvious once stated and invisible until then: the difference between what a product is made with and what it is made of.
The January 2020 issue of the journal Vaccine describes the method without controversy. The common rubella strain, RA27/3, was attenuated by passaging in human diploid fibroblasts, WI-38, at 30 and 35 degrees Celsius. Viruses cannot be grown in broth; they replicate only inside living cells, so a cell culture is the necessary medium. Once the virus has been weakened by repeated passage, it is harvested from that medium and purified.
The ingredient listing names WI-38 because manufacturers disclose what was used in production. That is transparency, and it is the reason the claim can cite a document at all. Read as a contents label, in the way people quite reasonably read the back of a cereal packet, it says something it was never saying. The disclosure meant to inform is the thing that misleads, which is an uncomfortable result for anyone who thinks more labelling is always the answer.
The question underneath is real, and it has an answer
It would be easy, and wrong, to treat everyone repeating this claim as confused about biology. Many are asking something coherent: if a medical product exists because of an abortion, am I implicated in that by accepting it?
That question is not answered by the purification step. It survives the fact-check intact, because it was never a question about the contents of the vial. And it has been examined seriously by the people with most at stake. As the BBC reported in 2020, institutions otherwise opposed to abortion, including the Catholic Church, have said that using vaccines produced this way is acceptable where no alternative exists, while pressing for alternative sources to be developed. One can accept or reject that reasoning. What one cannot say is that the question was ignored.
The scale matters to the moral arithmetic too. The 1962 line has been cultured ever since, and vaccine development has not required cells from any later abortion. WI-38 underlies vaccines against polio, measles, mumps, rubella, varicella, adenovirus, rabies and hepatitis A; a 2024 obituary for Hayflick in NPJ Aging estimated the beneficiaries at several billion people over fifty years. Whatever weight a person gives to the origin, the thing being weighed is one event in 1962, not an ongoing demand.
What the false version costs the people making it
Here is the part that ought to trouble anyone who holds the underlying objection sincerely. The false claim does not strengthen the moral case. It replaces it.
An argument about whether it is permissible to benefit from a cell line of this origin is one a person can actually pursue: there is a documented history, there is considered guidance from religious authorities, there is a live request for alternative lines to be developed. It leads somewhere. An assertion that the vial contains fetal tissue leads nowhere, because it is checkable and wrong, and once checked the entire position it was carrying gets discarded along with it.
So the people worst served by the strong version are the ones who care most about the question. They are handed a claim that feels decisive, and when it fails they are left looking as though their concern failed with it. It did not. It was simply attached to the wrong sentence.
The outbreak this is happening inside
None of this is taking place in the abstract. The CDC recorded the worst US measles outbreak since 1991: 2,777 cases from the start of 2026 to 20 August, 7% of them requiring hospitalisation, with three deaths reported in 2025 and none so far in 2026.
Harvard Medical School puts the immunisation level needed to suppress measles at about 95%. The national rate had fallen to 92% by 2023, and stood at 82% in the West Texas area where the 2025 outbreak began. Most of those infected in 2025 and 2026 were unvaccinated, of unknown vaccination status, or had received only one of the two scheduled doses.
Those are the recorded figures, set down here because the claim is being made in that context rather than in a vacuum. What any individual should do about their own or their family's vaccination is a matter for them and a doctor, and this file offers no advice on it. What it does say is narrower: the specific statement that the vial contains fetal tissue is false, the history of the cell line is true, and keeping those two apart is the whole of the work.
What's still unexplained
- Whether ingredient listings should distinguish more clearly between substances present in the finished product and materials used during manufacture, since the conflation of the two is doing all the work here.
- Whether alternative cell lines could replace WI-38 in rubella vaccine production, which is what the religious bodies that examined the question actually asked for, and what it would cost to do so.
- How much of the fall in US measles immunisation, from about 95% to 92% nationally by 2023 and to 82% in the area where the 2025 outbreak began, is attributable to claims of this kind rather than to access, cost or complacency.
- Whether a claim assembled this way, mostly accurate with one false conclusion, is best answered by a true-or-false rating at all, or whether the format itself hands the speaker the objection that the fact-check was unfair.
Point by point
The claim: WI-38 is listed in the MMR-II ingredients, so the cells are in the product.
What the record shows: An ingredient listing of this kind records what was used in manufacture, not only what remains at the end. The rubella virus is grown in the WI-38 culture and then extracted and purified, a step that removes the cells; no trace of them appears in the finished vaccine. The listing is honest disclosure of the production method, and reading it as a contents label is the single move on which the entire claim depends.
The claim: The cell line came from an aborted foetus, which the fact-checkers gloss over.
What the record shows: They do not, and neither does this file. WI-38 was isolated from the lung tissue of a foetus aborted legally in Sweden in 1962 and sent to Leonard Hayflick's laboratory. That is documented, uncontested, and recorded here in the timeline above. Establishing it does not establish anything about what the vial contains, which is a separate question with a separate answer.
The claim: Vaccine production therefore creates an ongoing demand for aborted fetal tissue.
What the record shows: It has not. The same 1960s line has been cultured continuously, and vaccine development has not needed to take new cells from more recent abortions. WI-38 underlies vaccines for at least eight diseases, with a 2024 estimate in NPJ Aging putting the beneficiaries at several billion people over fifty years. Whatever one concludes morally, the object of that judgement is a single historical event, not a continuing practice.
The claim: This is a religious objection that scientists refuse to engage with.
What the record shows: The engagement happened, publicly and some time ago. As the BBC reported in 2020, institutions otherwise opposed to abortion, the Catholic Church among them, have stated that using vaccines produced this way is acceptable where no alternative exists, while pressing for alternative sources to be developed. That is a considered answer to the real question, and it is available to anyone weighing it.
The claim: Fact-checkers call the whole statement false, which is obviously unfair when so much of it is right.
What the record shows: That objection has force, and it is worth stating precisely rather than waving away. Of the claim's components, the growth medium, the origin of the line and the ingredient listing are all accurate. What was rated false is the conclusion drawn from them: that portions of the cells end up in each vial. A rating attaches to the claim being tested, and here that claim was about the contents of the vaccine.
Timeline
- 1961Leonard Hayflick and Paul Moorhead publish their work on the serial cultivation of human diploid cell strains, establishing that ordinary human cells divide a limited number of times before dying, a boundary that becomes known as the Hayflick limit. The finding makes a stable, finite human cell line valuable for growing viruses.
- 1962A woman three months pregnant has a legal abortion in Sweden. As the author Meredith Wadman documents in The Vaccine Race, the foetus was not incinerated or buried; it was wrapped in sterile green cloth and sent to Hayflick, who isolated from its lung tissue the cell line designated WI-38. This is the event at the centre of the moral argument, and nothing in this file disputes that it happened.
- 1960s onwardWI-38 becomes the basis for producing vaccines against poliomyelitis, measles, mumps, rubella, varicella, adenovirus, rabies and hepatitis A. A 2024 obituary for Hayflick in the journal NPJ Aging estimates the number of people who have benefited over fifty years at several billion. No further abortions were required: the same 1960s line continued to be cultured.
- 2020-01-29An article in the medical journal Vaccine sets out the production method plainly. The most common rubella vaccine strain, RA27/3, was extracted using explant liver culture and attenuated by passaging in human diploid fibroblasts, WI-38, at 30 and 35 degrees Celsius. Growing a virus in a cell culture is the step the later claim describes correctly.
- 2020-11A BBC Future article on the cell line records that institutions otherwise opposed to abortion, including the Catholic Church, have publicly supported the use of vaccines manufactured this way where no alternative exists, while also expressing a need for alternative sources. The ethical question had already been asked, in public, and answered by the bodies whose members most needed an answer.
- 2025-04-30At a NewsNation town hall with Chris Cuomo, the US health secretary says the MMR vaccine contains a lot of aborted fetus debris. This is the loose version of the claim: emotive, imprecise, and easy to dismiss.
- 2026The CDC records the worst US measles outbreak since 1991: 2,777 cases from the beginning of 2026 to 20 August, 7% of them requiring hospitalisation, with three deaths reported in 2025 and none in 2026. Harvard Medical School notes that suppressing measles requires about 95% immunisation, that the national rate had fallen to 92% by 2023, and that it stood at 82% in the West Texas area where the 2025 outbreak began.
- 2026-08-25Responding on X to Pennsylvania Governor Josh Shapiro, who had accused him of peddling vaccine conspiracy theories, the health secretary restates the claim in a far more precise form: that the rubella virus in MMR-II is grown on a cell line composed of lung tissue from an aborted three-month-old female embryo, that it is listed as WI-38 human diploid lung fibroblasts in the ingredients, and that portions of these cells end up in each vial.
- 2026-09-01Snopes rates the claim false, on the specific ground that the vaccine does not contain fetal material. The virus is attenuated in the cells, then extracted and purified, removing all trace of WI-38.
Contradicted. This is one of the most precisely constructed false claims in the corpus, and taking it apart requires conceding most of it. In an X post on 25 August 2026 the US health secretary wrote that the rubella virus in MMR-II is grown on a cultured cell line composed of lung tissue from an aborted three-month-old female embryo, that this line is listed as WI-38 human diploid lung fibroblasts in the ingredients, and that portions of those cells end up in each vial. The first two points are accurate and the ingredient listing is real. The last is not: the attenuated virus is extracted from the culture and purified, and no trace of the WI-38 cells remains in the finished vaccine. Snopes rated the claim false. The verdict here applies to that single clause about what is in the vial, not to the history of the cell line, which is real and is a fair subject for moral argument. What this file rates is the substitution of a false empirical claim for an ethical question that can actually be answered.
Reviewed by The Conspiratory Editors · Last reviewed September 2, 2026 · How we rate
Common questions
Is Fetal tissue in MMR true?
Contradicted. This is one of the most precisely constructed false claims in the corpus, and taking it apart requires conceding most of it. In an X post on 25 August 2026 the US health secretary wrote that the rubella virus in MMR-II is grown on a cultured cell line composed of lung tissue from an aborted three-month-old female embryo, that this line is listed as WI-38 human diploid lung fibroblasts in the ingredients, and that portions of those cells end up in each vial. The first two points are accurate and the ingredient listing is real. The last is not: the attenuated virus is extracted from the culture and purified, and no trace of the WI-38 cells remains in the finished vaccine. Snopes rated the claim false. The verdict here applies to that single clause about what is in the vial, not to the history of the cell line, which is real and is a fair subject for moral argument. What this file rates is the substitution of a false empirical claim for an ethical question that can actually be answered.
What is Fetal tissue in MMR?
Almost everything in the claim is true, which is why it works. The rubella component of MMR-II really is grown using WI-38, a cell line really derived from lung tissue of a foetus aborted in Sweden in the early 1960s, and WI-38 really is named in the product's ingredient listing. The single false element is the conclusion: that portions…
What does the evidence show?
An ingredient listing of this kind records what was used in manufacture, not only what remains at the end. The rubella virus is grown in the WI-38 culture and then extracted and purified, a step that removes the cells; no trace of them appears in the finished vaccine. The listing is honest disclosure of the production method, and reading…
Why do people believe it?
The checkable parts check out. Someone who looks up WI-38, finds it named in the ingredients and finds its 1962 origin has verified three separate assertions and been right every time, which is a powerful reason to trust the fourth.
What is still unresolved?
Whether ingredient listings should distinguish more clearly between substances present in the finished product and materials used during manufacture, since the conflation of the two is doing all the work here.
Sources
- 1.No, the MMR vaccine does not contain fetal tissue, despite RFK Jr.'s claim, Snopes (2026)
- 2.The controversial cells that saved 10 million lives, BBC Future (2020)
- 3.After 100s of millions of safe MMR shots, Trump baselessly said the vaccine is possibly 'quite lethal', PolitiFact (2026)
- 4.Doctors don't inject kids with soda bottle's worth of vaccines. Trump's claim is Pants on Fire, PolitiFact (2026)
- 5.RFK Jr. and the claim that vaccines are never tested against a control group, Snopes (2024)
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