Controversial IgG4 Study On mRNA Vaccine Efficacy: What It Means Clinically

And what it means for IgG4-related diseases and cancer.

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Back in July 2022, a preprint finding a rise in IgG4 antibodies after repeated mRNA vaccination was used by the anti-vaccine community as proof that mRNA vaccines impair immunity against Covid-19.

Now that the preprint was formally published in Science Immunology last month, a similar anti-vaccine movement has resurfaced, additionally claiming that mRNA vaccines cause IgG4-related diseases and cancer. But the pro-vaccine community says otherwise — that increased IgG4 regulates inflammation and may improve disease outcomes.

So, I evaluated both sides of the argument and concluded that the pro-vaccine side is more reasonable, but ultimately, we don’t really know much about what the IgG4 study means clinically.

What the study did and found (feel free to skip)

Irrgang et al. from the University of Erlangen-Nuremberg, Germany, conducted the study, titled “Class switch towards non-inflammatory, spike-specific IgG4 antibodies after repeated SARS-CoV-2 mRNA vaccination.”

The study recruited 29 (median age of 44, 55% female) healthcare workers who got three doses of mRNA…