Every so often, a study emerges that makes you stop. Not because it tells you something you have never heard before, but because it confirms what you had feared all along.
This week, a new paper out of Japan did exactly that.
The study, published on April 15, 2025, was titled Repeated COVID-19 Vaccination as a Poor Prognostic Factor in Pancreatic Cancer. It was a retrospective single-center study, not yet peer reviewed. But it sent a powerful message. In patients with pancreatic cancer, those who had received three or more COVID-19 vaccine doses had significantly shorter survival. At the same time, these patients showed increased levels of a specific antibody known as IgG4.
I have spoken about this before. Eighteen months ago, I released a presentation outlining why IgG4 responses after repeated mRNA vaccination could have unintended immune consequences. At the time, few people were listening. Now, it appears those warnings were not misplaced.
The Role of IgG4 in Immunity and Cancer
Let me explain why this matters.
Our immune system produces different types of antibodies, known as immunoglobulins. IgG1 and IgG3 are powerful defenders. They trigger inflammation and help destroy threats like viruses and abnormal cells. IgG4, on the other hand, is the peacekeeper. It calms the immune response. In some situations, like allergy desensitization, this is helpful.
But in the context of cancer, tolerance is dangerous. You want your immune system to remain aggressive against cancer cells. When you increase IgG4, you risk sending the wrong signal. You risk telling the immune system to back off, just when it should be attacking.
What the Japanese researchers found was concerning. Patients who had received multiple COVID-19 vaccine doses had elevated IgG4 levels. At the same time, their IgG3 levels declined. This immune shift correlated with worse survival in pancreatic cancer.
An Immunological Red Flag
The mRNA vaccines have always been described as safe and effective. But the immune system is not a one-size-fits-all tool. Repeated exposure to the same spike protein sequence seems to be inducing an unusual antibody switch. After the third dose, researchers found an almost 4,000 percent increase in IgG4 in some individuals.
That is not a subtle change. It is a transformation of how your immune system responds.
In the context of infection, this may contribute to viral persistence. In the context of cancer, it may impair immune surveillance. The Japanese study did not prove causation, but the trend is clear and the implications are serious.
What the Data Showed
The researchers tracked pancreatic cancer patients over several years, comparing survival before and after the vaccine rollout. They found that survival rates declined after 2021. But more importantly, those who had received three or more vaccine doses had the worst outcomes.
When they analyzed the tumors, they found higher levels of regulatory immune cells in the tissue. These cells, like IgG4 antibodies, play a suppressive role. They help prevent overreaction. But again, in cancer, that is not what you want. You need your immune system fully engaged.
The study also found a clear correlation between rising IgG4 levels and poor prognosis.
Science Needs Curiosity, Not Denial
It is important to emphasize that this study has limitations. It comes from a single center. It focuses on one type of cancer. It is still awaiting peer review.
But here is the truth. Science does not advance by waiting for permission. It advances by asking hard questions and investigating concerning signals. The Japanese team did what other researchers have failed to do. They looked beyond the narrative and into the tissue. They followed the immune markers. They paid attention to outcomes.
And their findings are too important to ignore.
Where We Go From Here
We need more research. We need to replicate these findings in larger cohorts and across different cancer types. We need to understand how many people are experiencing long-term immune changes after vaccination and whether this affects their ability to fight not just cancer, but other chronic illnesses.
And we need to be honest. If a therapy intended to protect people is found to carry unexpected risks in vulnerable populations, the correct response is not silence. It is investigation, open dialogue, and course correction.
My Final Word
I have spoken about this topic for years. Often with frustration. Often feeling like my words are reaching deaf ears. But today, I feel a shift.
The science is catching up.
The question is, will the world pay attention before more lives are lost?
Thank you to the researchers in Japan. And thank you to those of you who are still willing to ask questions.
If you want to see my original presentation that predicted these issues, the link is included below. We must stay vigilant. Science is not a destination. It is a journey.
And the journey continues.
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