Are Preservatives and Adjuvants the Hidden Risk in Vaccines?

When people hear “vaccine,” they picture the antigen—the tiny piece of virus or bacteria that teaches your immune system what to fight. But vaccines aren’t just antigens. They’re delivered in a fluid that can include adjuvants (immune boosters), preservatives (to keep multi-dose vials sterile), stabilizers, buffers, and other excipients. Public agencies list these ingredients openly; examples include aluminum salts (adjuvants), MF59 or AS03 (oil-in-water emulsions), thimerosal or 2-phenoxyethanol (preservatives), and polysorbate 80 (an emulsifier).

One of the biggest shortcomings in current vaccine research is that studies often treat vaccination as an all-or-nothing question, without distinguishing between the antigen itself and the additives in the suspension fluid. A recently circulated testimony highlighting an unpublished “Henry Ford” analysis compared children who received any vaccines with those who received none and reported higher rates of asthma, autoimmune, atopic, and neurodevelopmental diagnoses among the vaccinated. But the analysis does not separate antigens from adjuvants, preservatives, or other excipients; it can’t tell us which component—if any—is driving associations. In short, it’s ingredient-agnostic so that no ingredient-level conclusions can be drawn.

Here’s a reasonable, evidence-based hypothesis that deserves serious study: if there’s a signal, it may stem from the suspension solution and its additives, not necessarily the antigen itself. Many protein or inactivated-virus antigens are weak stimulators on their own; adjuvants are added to provoke a stronger response. That’s their job. But by design, adjuvants and other additives interact with the immune system, which is precisely why we should evaluate them ingredient-by-ingredient, dose-by-dose, across schedules. Reviews describe how aluminum salts and emulsion adjuvants (MF59, AS03) recruit immune cells and amplify responses; that’s useful for protection, but it also frames the right research question: where’s the optimal benefit-risk line for each population and product?

We can’t debate the wins. Vaccines have beaten back diseases that plagued humanity for centuries. My father-in-law contracted polio as a boy, and it marked him for life. Just a few years later, the polio vaccine was invented—and a few years after, polio was wiped out in the United States. The same story holds for measles, mumps, rubella, and more. We can honor those victories while still demanding the safest possible formulations for the next generation.

So where does that leave us? With a commonsense path forward:

1. Do ingredient-level science. If a study reports associations with “any vaccination,” it should be followed by analyses that stratify by adjuvant, preservative, and formulation, not just antigen or dose count. Without that, we can’t identify (or clear) specific culprits.
2. Prefer cleaner formulations where feasible. Single-dose vials (no preservative needed), lyophilized products reconstituted with sterile saline, or platforms/formulations that avoid adjuvants for populations that don’t require them should be prioritized where supply and efficacy allow. (Not every vaccine can skip adjuvants; some antigens simply won’t protect a person without them.)
3. Update policy with transparency. Agencies already publish excipient lists; they should also fund head-to-head trials comparing adjuvanted vs. non-adjuvanted and preservative-free vs. preserved versions, with long-term follow-up on asthma, atopic, autoimmune, and neurodevelopmental outcomes. That’s the level of clarity parents deserve.

Bottom line: We can acknowledge two truths at once—vaccines are a cornerstone of public health, and formulation choices matter. If there’s an ingredient-related signal, the responsible course is not to speculate, but to measure it precisely and engineer it away. Cleaner suspension solutions—free of preservatives where practical and using the mildest effective adjuvants—are a unifying goal we should all support.