III. TECHNICAL CONTEXT: STERILIZING IMMUNITY AND REGULATORY DEFINITIONAL SLIPPAGE 

The concept of sterilizing immunity—the complete elimination of a pathogen before it can replicate in the host[1]—has long served as the gold standard for vaccine evaluation. Yet no vaccine has ever been 100% effective in achieving it[2]. This is not a new insight. In fact, when the CDC revised its public definition of "vaccine" in September 2021, its stated reason—quoted in an AP fact check—was precisely that[2]: 

“The previous definition could be interpreted to mean that vaccines were 100% effective, which they never have been”. 

That statement is technically correct. Even among traditional vaccines, real-world performance varies. Consider the mumps component of MMR: outbreaks today occur primarily among vaccinated populations[3], and immunity is known to wane substantially after 20–30 years[4,5]. A 2022 review noted that even two doses conferred only 88% median effectiveness[5], with lower efficacy against circulating genotype G strains[6]. Similarly,...