The Claim:
On Del Bigtree’s internet show, lawyer Aaron Siri claims that the whole childhood vaccine schedule is unsafe because, according to him, none of the vaccines were ever tested the right way with real placebo groups.
The Facts:
Siri says that most childhood vaccines are tested against other vaccines instead of a simple salt-water placebo. But in real life, many vaccines have been tested using saline placebos to check safety and how well they work, including:
- Rubella vaccine
- Pneumococcal vaccine
- Hib vaccines
- HPV vaccine
- The Salk Polio vaccine
- Measles vaccine
- Tdap vaccine
- COVID vaccine
Sometimes a new vaccine is compared to an older vaccine, or the placebo may have tiny amounts of things like adjuvants or stabilizers that scientists already know are safe.
The World Health Organization has rules for when using a placebo is fair and safe. It is okay to use a placebo when no good vaccine exists yet and the study could help protect people. But if a country already has a safe, effective vaccine, it is not ethical to give people a placebo instead, because that would leave them unprotected and at risk.
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Glossary words on this page
- Adjuvant
- Adjuvants are “booster” ingredients – they help your body produce a stronger immune response which means greater protection against a disease.
- Haemophilus influenzae type b (Hib)
- A bacterium that may result in severe respiratory infections, including pneumonia and other diseases such as meningitis.
- Measles
- Measles is the most contagious viral illness.
- Placebo
- A substance that cannot prevent or treat disease.
- Poliomyelitis (polio)
- Poliomyelitis (polio) is a viral infection that is spread person-to-person through the fecal-oral route.
- Rubella (German Measles)
- A viral infection with a red rash, enlarged neck lymph nodes, mild fever, and headache.
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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