Fact Check: Is Robert F Kennedy Jr’s claim that the MMR vaccine contains fetal tissue true?
WASHINGTON, DC: US Health Secretary Robert F Kennedy Jr has claimed that the measles, mumps and rubella (MMR) vaccine contains fetal tissue. The claim has sparked debate online and raised questions about how the vaccine is made and what ingredients it contains. Let's fact-check the claim.
Claim: RFK Jr says MMR vaccine contains 'fetal issue'
At his press conference today, Pennsylvania Governor Josh Shapiro accused me of promoting conspiracy theories because I told him, during an earlier telephone conversation, that some Americans had religious objections to the MMR vaccine because it contained fetal tissue. “There is…
— Robert F. Kennedy Jr (@RobertKennedyJr) August 26, 2026
In August 2026, US Health Secretary Robert F Kennedy Jr claimed in an X post that the measles, mumps and rubella (MMR) vaccine contains “fetal tissue.”
Kennedy made the claim while responding to Pennsylvania Governor Josh Shapiro, a Democrat, who accused him of promoting conspiracy theories about vaccines.
In an August 25 X post, Kennedy defended his claim. He said the rubella virus used in MMR-II is grown on a cell line called WI-38, which was developed from lung tissue taken from a three-month-old female fetus after an abortion. Kennedy also claimed that portions of these cells remain in each MMR-II vial.
This was not the first time Kennedy made a similar claim. During a NewsNation town hall with television presenter Chris Cuomo on April 30, 2025, he said the MMR vaccine contains “a lot of aborted fetus debris.”
Fact Check: The claim is false
The claim is false. Robert F Kennedy Jr’s statement that the MMR vaccine contains fetal material from abortions is incorrect. The claim comes as the US faces its worst measles outbreak in decades.
According to the Centers for Disease Control and Prevention (CDC), the country recorded 2,777 measles cases between the start of 2026 and August 20. About 7% of those patients required hospitalization.
The CDC has also reported three measles deaths in 2025 and none in 2026 as of that date. Measles spreads easily, and Harvard Medical School says about 95% of the population needs to be vaccinated to prevent outbreaks. The US maintained vaccination rates at or above that level for years, which helped limit the spread of measles. However, vaccination rates have declined in recent years.
The rate fell to 92% in 2023, while vaccination coverage in the area of West Texas where the 2025 outbreak began was about 82%, according to Harvard Medical School.
Health experts have long linked misinformation and disinformation to fears about the safety of the MMR vaccine and other vaccines. Kennedy has also repeatedly promoted false claims about vaccines.
Notably, MMR protects against measles, mumps, and rubella by using three live but weakened viruses. These weakened viruses do not normally cause the diseases but train the immune system to recognize and fight them.
