The Claim:
In a CBS news interview, HHS Secretary RFK Jr. claims that immunity from the MMR vaccine wanes quickly in order to explain why the measles outbreaks are spreading farther and longer than they might otherwise.
The Facts:
The claim that the MMR wanes quickly is untrue. Even if the antibodies your body makes from the vaccines lessen over time, your immune system still remembers the virus using special memory cells. These memory cells usually remain in your body for your entire life, able to respond quickly and protect you from measles if you’re ever exposed.
Also, measles is so contagious that if a person susceptible to measles walks into a room where someone with measles had been two hours prior and left, 90% of those people would still get measles. Before the vaccine was available, nearly everyone got measles.
If the measles vaccine were waning quickly, as Kennedy claims, leaving a large number of people susceptible, we would see a huge number of vaccinated people getting measles. But that’s not what we are seeing. Of 561 cases identified, 550 of them are unvaccinated, while only 11 have had only one or two vaccine doses. We know that one dose of MMR protects up to 93% of people while two doses protect up to 97% of people, and these numbers track what we’d expect if the vaccine was working as expected.
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Glossary words on this page
- Antibody
- An antibody is part of the immune system that recognizes foreign substances like bacteria and viruses (antigens) and fights them.
- Immune system
- The complex system in the body responsible for fighting disease.
- Immunity
- Protection against a disease.
- Measles
- Measles is the most contagious viral illness.
- Memory cells
- A group of cells that help the body defend itself against disease by remembering prior exposure to specific viruses or bacteria.
- Outbreak
- When cases of a disease spreads beyond what is normal, infecting a lot of people in a defined population or area.
- Susceptible
- When you are at risk of getting a disease because you are not protected against it.
- Virus
- A tiny organism that multiplies within cells and causes diseases such as chickenpox, measles, mumps, rubella, and hepatitis.
Disclaimer
Science is always evolving and our understanding of these topics may have evolved too since this was originally posted. Be sure to check out our most recent posts and browse the latest Just the Facts Topics for the latest.
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