CIDRAP Op-Ed: Measles, misinformation, and what’s actually in the MMR vaccine

Greater than 4,000 People have contracted measles since January 2025. Two kids and one grownup have died. Sixteen states have fallen under the vaccination threshold required to stop sustained transmission. The USA is prone to shedding its measles elimination standing, which it achieved in 2000.

Secretary of Well being and Human Providers Robert F. Kennedy Jr. has a message for the communities on the heart of those outbreaks: the measles, mumps, and rubella (MMR) vaccine accommodates “hundreds of thousands of particles that have been created from aborted fetal tissue, hundreds of thousands of DNA fragments.” It doesn’t.

He’s the nation’s chief public well being officer. He’s making this declare in the course of the worst measles outbreak in additional than three a long time. He’s making it concerning the one vaccine that would cease that outbreak. And he’s directing it on the non secular communities—Mennonite, Orthodox, conservative Catholic—wherein vaccination charges are lowest and the place the present instances are concentrated.

Let’s discover what the manufacturing, regulatory, and scientific data truly present.

The place the vaccine comes from

Viruses can replicate solely inside residing cells. To make the rubella element of the MMR vaccine, producers develop the reside weakened virus in a human cell pressure referred to as WI-38. 

In 1962, a researcher named Leonard Hayflick remoted cells from lung tissue obtained from a single elective abortion carried out in Sweden. These cells have been positioned in laboratory cell cultures—managed environments the place cells are grown outdoors the physique—the place they’ve been propagating ever since. The cell pressure utilized in Merck’s MMR-II traces its lineage to that unique tradition. 

The chickenpox and hepatitis A vaccines use an analogous pressure, MRC-5, established in 1966 by J.P. Jacobs from lung cells obtained from an elective abortion carried out in the UK.

Each of those info come straight from the product pages of the American Sort Tradition Assortment, the nationwide repository that catalogs and sells organic supplies to researchers—the identical database cited by these making these claims.

These cell strains will not be immortal. They replicate for roughly 50 passages, then attain the tip of their replicative lifespan. Producers keep frozen seed shares that may be thawed to begin contemporary cultures as wanted. This finite nature is a security characteristic: It distinguishes these strains from steady cell strains, which replicate indefinitely and carry a theoretical most cancers threat.

These cell strains will not be immortal. They replicate for roughly 50 passages, then attain the tip of their replicative lifespan.

The cells used right now are the laboratory descendants of these unique strains, not materials from any abortion. The unique cells haven’t existed for sixty years. No new abortions are carried out to fabricate these vaccines.

As soon as the virus finishes rising in these cell cultures, it’s extracted and purified. What results in the ultimate vaccine is the weakened virus, stabilizing substances, and hint quantities of residual protein and DNA left over from the manufacturing course of. There are not any intact human cells within the vaccine.

The residual DNA query

Hint quantities of DNA from the WI-38 pressure do stay within the closing product. It is a recognized manufacturing actuality, disclosed within the package deal insert, and studied extensively by regulators. Their conclusion: Residual DNA from regular human cell strains like WI-38 and MRC-5 doesn’t pose a security threat.

That willpower requires some context. The World Well being Group (WHO) units a strict restrict of 10 nanograms of residual DNA per vaccine dose. That restrict was established particularly for a distinct class of manufacturing cells referred to as steady cell strains, which may be derived from tumors and carry theoretical most cancers threat. WI-38 and MRC-5 will not be in that class. They’re regular, finite human cell strains with no capability to kind tumors, and WHO steering explicitly states that the 10-nanogram restrict doesn’t apply to merchandise constructed from regular human cell strains like these.

The DNA fragments that stay are deliberately lowered to under 200 base pairs in size. A base pair is the essential structural unit of DNA. The typical human gene is 1000’s to tens of 1000’s of base pairs lengthy. A 200 base pair fragment can’t encode a purposeful protein or combine meaningfully right into a human genome. 

The Meals and Drug Administration’s advisory committee evaluated the mobile DNA within the chickenpox vaccine, which accommodates the best DNA content material of any accepted childhood vaccine, and concluded particularly that it was unlikely to combine into host cells and trigger hurt throughout vaccination.

The “billions of fragments” determine that circulates extensively on-line comes from actual arithmetic utilized to a negligible mass. A nanogram is a billionth of a gram. If you divide nanograms of DNA by the size of every fragment, you get an infinite fragment rely. You don’t get a biologically significant amount of fabric.

The paper behind the autism declare

The declare that vaccine DNA causes autism traces nearly completely to a 2015 paper by Theresa Deisher and colleagues, printed in Points in Regulation and Drugs. That journal is printed by the Alliance for Hippocratic Drugs, a right-to-life advocacy group. It isn’t a molecular biology or epidemiology journal.

The paper makes two primary arguments.

The primary examines MMR vaccination charges and autism diagnoses in the UK, Norway, and Sweden in the course of the years following Andrew Wakefield’s 1998 Lancet paper—the fraudulent research that falsely linked the MMR vaccine to autism, was formally retracted, and value Wakefield his medical license. After this publication, MMR vaccination protection dropped throughout Britain and Scandinavia. Deisher argues that autism diagnoses additionally fell throughout this era and that this constitutes a “pure experiment” proving the vaccine causes autism via its fetal DNA content material.

Two issues undercut this completely. The paper’s personal authors acknowledge that publicly obtainable autism prevalence information for this era is “disappointingly scarce.” And the obvious drop in diagnoses in the course of the top of the Wakefield panic nearly actually displays disrupted pediatric care, not a real fall in autism charges. When dad and mom cease bringing kids to docs out of concern, fewer kids get recognized. The truth that two traits moved in the identical course throughout a interval of social disruption will not be proof that one prompted the opposite.

The obvious drop in diagnoses in the course of the top of the Wakefield panic nearly actually displays disrupted pediatric care, not a real fall in autism charges.

The second a part of the paper describes laboratory experiments wherein DNA fragments have been added to most cancers cells in lab dishes and noticed to enter these cells. Cells in a dish behave very in another way from cells in a residing individual. For vaccine-derived DNA to trigger autism would require a sequence of occasions that has by no means been demonstrated: DNA surviving the physique’s fixed degradation of overseas materials, touring from the injection web site, crossing the blood-brain barrier, coming into neurons, and integrating at exactly the suitable genomic location to disrupt autism-associated genes. 

Additionally, Deisher’s measurements have been taken from Meruvax II, Merck’s discontinued standalone rubella vaccine, not from MMR-II. The info getting used as proof of hazard within the MMR vaccine weren’t even collected from the MMR vaccine.

The Deisher paper will not be a brand new scientific discovering. It’s an try to revive the Wakefield speculation with a distinct proposed mechanism, utilizing the identical sort of comparability that gave Wakefield’s argument its superficial plausibility.

The non secular argument

Secretary Kennedy cited Mennonite communities’ objections because the context for his declare. The Catholic Church, which holds essentially the most theologically developed place on this query amongst main Christian denominations, has examined it fastidiously. 

In 2005, the Vatican’s Pontifical Academy for Life formally evaluated the ethics of vaccines made utilizing fetal cell strains. Its 2017 follow-up assertion concluded that receiving these vaccines includes no morally related cooperation with the unique abortions. A 2020 assertion from the Congregation for the Doctrine of the Religion concerning COVID vaccination, accepted by Pope Francis, confirmed that receiving vaccines made utilizing these cell strains is morally acceptable given the gravity of preventable illness.

The establishment most publicly dedicated to opposing abortion has concluded that these vaccines could also be utilized in good conscience.

The toll on children of deceptive claims

The unique Wakefield fraud drove down MMR protection throughout the UK and prompted measles outbreaks that contaminated 1000’s of youngsters. The identical argument—now amplified by the highest US public well being official, focused on the communities most in danger, throughout an lively outbreak of the illness it discourages folks from stopping—is contributing to the outbreaks below manner now.

MMR vaccination charges amongst kindergartners have fallen from 95.2% to 92.5% nationally. Two kids died from measles in 2025, the primary pediatric measles deaths on this nation in additional than a decade, from a illness for which we’ve had a secure and efficient vaccine since 1963.

The establishment most publicly dedicated to opposing abortion has concluded that these vaccines could also be utilized in good conscience.

The declare that the MMR vaccine accommodates aborted fetal tissue is fake. The hint residual DNA it does include has been evaluated by regulators, discovered to not pose a security threat, and administered safely to a whole bunch of hundreds of thousands of individuals throughout six a long time.

Worry about vaccine substances, contradicted by 60 years of security information, has pushed vaccination charges to the purpose the place kids are dying from a illness we eradicated a era in the past.

Dr. Scott is a Medical Affiliate Professor of Infectious Illnesses at Stanford College Faculty of Drugs and a co-author of “Up to date Proof for Covid-19, RSV, and Influenza Vaccines for 2025-2026“ within the New England Journal of Drugs.

The opinions voiced in CIDRAP Op-Ed items are the authors’ personal and don’t essentially symbolize the official place of CIDRAP.