American vaccines are validated with randomized, double-blind and placebo-controlled studies.

This means that these studies are rigorously designed to minimize bias and ensure accurate findings.
These are also large, lengthy and expensive studies.

Placebo controlled means that participants are randomly assigned to receive either
the experimental vaccine or a placebo.

A placebo is an inactive injection that mimics the real experience to the patient.

Double blind means that neither the participants nor researchers know who is receiving the vaccine or the placebo.

The flu and covid vaccines receive yearly updates to reflect the mutating viruses each year.
These vaccines have already been tested thoroughly as stated above.
But the yearly updates are not placebo studies because it is unethical to withhold
a needed preventive medication. They do undergo randomized and double blind studies.

Forcing researchers to start from scratch and replicate all previous research would be
expensive, time consuming and in effect prevent yearly updated vaccines.
It would be like being told that to paint the interior of your newer home, you need to to get
local, state, and federal inspections.

RFKjr has no idea how research is conducted. Researchers make excellent research protocols
but they must be done ethically. He is just looking for a way to prevent vaccine boosters.