The New mRNA Flu Vaccine: The Questions I Couldn't Find Answers To

Before You Roll Up Your Sleeve

This isn't an article telling you what to do. It's an article about the questions I went looking for—and the answers I found, or couldn't find—in the publicly available science behind the first mRNA influenza vaccine - mFLUSIVA. I also can't ignore history, having lived through it. The first widespread use of an mRNA-lipid nanoparticle platform occurred during the COVID-19 pandemic, and many questions remain. So, regardless of where one stands in the debate, I believe these questions deserve to be revisited whenever a new mRNA-lipid nanoparticle vaccine is introduced, if only for your own knowledge.

For more than 30 years, I've been asking a simple question: What happens to the human body after it's exposed to a chemical? Whether I'm looking at mercury, lead, BPA, phthalates, pesticides, mold toxins, or pharmaceuticals, I ask the same questions:

• Where does it go?
• How long does it stay?
• What organs does it affect?
• How is it metabolized?
• What happens after repeated exposure?
• What human evidence answers those questions?

When I heard about the first mRNA flu vaccine, I approached it the same way, but I had a few additional questions specific to the technology. I wanted to know:

• How long do human cells continue producing influenza hemagglutinin after vaccination? Has anyone measured how long that protein is produced in humans?
• What happens to the lipid nanoparticles after they've delivered the mRNA?
• How are SM-102 and PEG-2000-DMG - 2 ingredients in the vaccines - metabolized in humans? Do these components or their metabolites accumulate after repeated yearly exposure?
• What happens when anti-PEG antibodies develop, in some cases to the tune of 10X?
• Were these questions studied directly in people receiving mFLUSIVA, or were they inferred from Moderna's existing mRNA platform?
• What long-term human evidence exists—not months, but years?
  

I was surprised by how many of those questions were only partially answered—or weren't answered at all in the available studies. That doesn't mean the answers don't exist. It just means I couldn't find them in the evidence that regulators, healthcare professionals, and the public are expected to rely on when evaluating this new vaccine.

That became the reason for writing this article.

Why the COVID-19 Experience Matters

The reason is simple. Although the protein being produced is different, the underlying mRNA-lipid nanoparticle platform is closely related. Questions that emerged during the widespread use of that platform did not disappear simply because the target protein changed from the SARS-CoV-2 spike protein to influenza hemagglutinin.

If anything, those questions become even more relevant when the same technology is proposed for repeated annual use.

The first thing I wanted to know was remarkably simple: What question were the clinical trials actually designed to answer? The answer was that the studies were designed to determine whether mFLUSIVA could prevent influenza (lab-confirmed) in adults, and if its safety profile supported approval. Those were its primary endpoints.

But I began asking whether the studies themselves were designed to answer the biological questions that mattered most to me:
Who was actually studied? What were the researchers trying to measure? How did they define success? And just as importantly, what weren't they trying to measure?

I realized I was looking for answers to questions the studies were never designed to answer. I couldn't find evidence showing how long human cells continue producing hemagglutinin after vaccination, or whether that production varies from one person to another. And most importantly, I couldn't find studies following people for years to determine whether those receiving annual mRNA flu vaccines experience different long-term outcomes than comparable people who do not. Of course these don't exist because the studies took place over 1 flu season. 

The most obvious question of all:

It surprises me to discover that this isn't a question the pivotal clinical trials were designed to answer. It certainly was when I did my own dissertation (a control group was just that - no intervention). Instead, the primary comparison was between mFLUSIVA and another flu vaccine. In other words, researchers were asking whether one vaccine performed better than another under the conditions of the study—not whether people receiving repeated annual mRNA influenza vaccines experience different long-term health outcomes than similar people who never receive them. But how could this possibly be answered if there were no long-term trials to report?

More Questions I Couldn't Find Answers To

I still wanted to know exactly what constituted an acceptable safety profile, how long participants were actually followed, and what was—and wasn't—being measured.

I specifically wanted to know:
Exactly what constituted an acceptable safety profile?
How long were participants actually followed?
Which adverse events were actively monitored, and for how long?
What happened during the first 14 days after vaccination?
How was influenza defined and confirmed?
Were participants ever compared with similar people who did not receive an mRNA influenza vaccine?

What Counted as "Influenza"?

One of the first things I wanted to understand was how the researchers determined whether someone actually had "the flu." The answer was RT-PCR testing, which is excellent for detecting genetic material but not whether a virus is alive, whether it is capable of causing disease, or whether it is actively replicating. It detects genetic material, period.

That distinction matters because the primary endpoint of the study depended on identifying lab-confirmed influenza.

Another Question Rises Up

I looked for details describing exactly how the PCR testing was performed, including the cycle threshold (Ct) values used to define a positive result, but I couldn't find that information. That doesn't necessarily mean the information doesn't exist; it just means I couldn't find it in the publicly available material supporting the approval. However, without those details, we cannot seriously evaluate the primary measurement used to determine whether the vaccine prevented influenza, in my humble opinion.

This wasn't a new question for me. I've been raising it for years. My concern has never been PCR as a laboratory tool; it's the use of PCR as the foundation for diagnosing disease and measuring vaccine effectiveness. When a study's primary claim of effectiveness rests on "laboratory-confirmed influenza," I believe the laboratory methods become just as important as the statistical results. If we don't know exactly how a positive influenza case was defined, it becomes much harder to independently evaluate the conclusions drawn from the study.

What Happens After the Injection?

Unlike a traditional flu vaccine, mFLUSIVA delivers synthetic mRNA inside lipid nanoparticles. Once those particles enter human cells, the cells begin producing influenza hemagglutinin—the viral protein the immune system is meant to recognize.

From there, my questions became surprisingly simple:
How long do human cells continue producing that protein?
Has anyone measured it directly in people receiving mFLUSIVA?
Does production vary from one person to another?
Does age, underlying health, genetics, or previous exposure to mRNA vaccines influence the amount or duration of protein production?
And if this vaccine is intended to be given year after year, what do we know about repeated cycles of protein production over time?

Those are not small questions. As I reviewed the publicly available studies supporting mFLUSIVA, I looked for direct human evidence answering them. I couldn't find it.

Looking More Closely at the Ingredients

My attention then shifted to another part of the equation: the delivery system itself. As an experienced toxin lab interpreter, I immediately began thinking about the metabolites.

A metabolite is simply a new chemical created when the body begins breaking down another chemical. In my practice, I'm often less interested in the original substance than in the metabolites it leaves behind. Whether I'm reviewing pesticides, BPA, phthalates, solvents, mold toxins, or pharmaceuticals, those metabolites often tell us how the body processed the exposure—and sometimes raise new questions of their own. I approached the lipid nanoparticle ingredients in mFLUSIVA exactly the same way.

For SM-102, there was remarkably little publicly available human evidence describing how it's metabolized after injection. I couldn't find detailed human studies identifying the metabolites it forms, how long those metabolites remain in the body, whether they preferentially distribute to certain tissues, or whether repeated annual exposure changes those processes.

PEG-2000-DMG has been investigated more extensively. Recent research has shown that it does not simply disappear after entering the body. Instead, it is broken down into numerous smaller compounds, including oxidized PEG fragments and aldehyde-containing metabolites. In other words, once PEG enters the body, it becomes a different collection of chemicals through normal metabolism.

One Finding That Did Stand Out

Several human studies reported that some individuals developed measurable anti-PEG antibodies after receiving Moderna's mRNA platform vaccines. In one study, about one-third of participants developed anti-PEG antibody levels roughly 10 times higher than before vaccination, and those elevations persisted for more than six months. The authors concluded that the long-term clinical significance remains unknown.

Where My Search Ended

I didn't write this article because I expected to find evidence proving harm. I wrote it because I expected to find answers to the same toxicological questions I ask about every other chemical exposure I evaluate.

• Where does it go?
• How long does it stay?
• What metabolites are formed?
• What happens after repeated exposure?
• What do long-term human studies show?

My Bottom Line

After reviewing the publicly available science behind mFLUSIVA, my position hasn't changed—it has been reinforced. Too many unanswered questions involving repeated annual exposure to an mRNA-lipid nanoparticle platform, too little long-term human evidence addressing the biological questions I consider most important, and too much reliance on assumptions carried over from an existing platform rather than direct human data answering those questions.

I would not accept this level of uncertainty for a pesticide, an industrial chemical, a pharmaceutical, or any other substance introduced into the human body. I see no reason to apply a different standard here.

My goal isn't to tell you what to do. My goal is to encourage you to ask the same questions before making your own decision.