The IgG4 Puzzle: Why Boosters May Weaken One Defense but Strengthen Another
Post-Vaccination IgG4 and IgG2 Class Switching is linked to Increased Risk of SARS-CoV-2 Infections A new study published in Infectious Disease Practice has revealed a concerning correlation between the class switching of antibodies after COVID-19 mRNA booster vaccinations and a heightened risk of breakthrough infections. Specifically, the study found that elevated levels of IgG4 and IgG2 antibodies, which increase significantly following the third mRNA dose, are linked to an increased risk of symptomatic SARS-CoV-2 infections. The study followed a longitudinal cohort of 83 healthcare workers who received three vaccine doses, with an additional 66 participants analyzed at a specific timepoint (T9, May 2022), four months after the first booster. Conducted in Spain, the research tracked immune responses over nearly three years, revealing that the proportion of non-cytophilic antibodies (IgG4 and IgG2) increased relative to cytophilic subclasses (IgG1 and IgG3) after the booster. Th...