Role of anti-polyethylene glycol (PEG) antibodies in the allergic reactions and immunogenicity of PEG-containing Covid-19 vaccines

The polyethylene-glycol (PEG)-containing Covid-19 vaccines can cause hypersensitivity reactions (HSRs), or rarely, life-threatening anaphylaxis. A causal role of anti-PEG antibodies (Abs) has been proposed, but not yet proven in humans. The 191 blood donors in this study included 10 women and 5 men who displayed HSRs to Comirnaty or Spikevax Covid-19 vaccines with 3 anaphylaxis. 118 donors had pre-vaccination anti-PEG IgG/IgM values as measured by ELISA, of which >98% were over background regardless of age, indicating the presence of these Abs in almost everyone. Their values varied over 2-3 orders of magnitude and displayed strong left-skewed distribution with 3-4% of subjects having >15-30-fold higher values than the respective median. First, or booster injections with both vaccines led to significant rises of anti-PEG IgG/IgM with >10-fold rises in about [~]10% of Comirnaty, and all Spikevax recipients, measured at different times after the injections. The anti-PEG Ab levels measured within 4-months after the HSRs were significantly higher than those in nonreactors. Serial testing of plasma (n=361 tests) showed the SARS-CoV-2 neutralization IgG to vary over a broad range, with a trend for biphasic dose dependence on anti-PEG Abs. The highest prevalence of anti-PEG Ab positivity in human blood reported to date represents new information which can most easily be rationalized by daily exposure to common PEG-containing medications and/or household items. The significantly higher, HSR-non-coincidental blood level of anti-PEG Abs in hypersensitivity reactor vs. non-reactors, taken together with relevant clinical and experimental data in the literature, suggest that anti-PEG Ab supercarrier people might be at increased risk for HSRs to PEG-containing vaccines, which themselves can induce these Abs via bystander immunogenicity. Our data also raise the possibility that anti-PEG Abs might also contribute to the reduction of these vaccines virus neutralization efficacy. Thus, screening for anti-PEG Ab supercarriers may identify people at risk for HSRs or reduced vaccine effectiveness.