Endotyping of IgE-Mediated Polyethylene Glycol and/or Polysorbate 80 Allergy.

BACKGROUND: Polyethylene glycol (PEG) and polysorbate 80 (PS80) allergy preclude from SARS-CoV-2 vaccination. The mechanism(s) governing cross-reactivity and PEG molecular weight dependence remain unclear. OBJECTIVES: To evaluate PEGylated lipid nanoparticle (LNP) vaccine (BNT162b2) tolerance and explore the mechanism of reactivity in PEG and/or PS80 allergic patients. METHODS: PEG/PS80 dual- (n = 3), PEG mono- (n = 7), and PS80 mono-allergic patients (n = 2) were included. Tolerability of graded vaccine challenges was assessed. Basophil activation testing on whole blood (wb-BAT) or passively sensitized donor basophils (allo-BAT) was performed using PEG, PS80, BNT162b2, and PEGylated lipids (ALC-0159). Serum PEG-specific IgE was measured in patients (n = 10) and controls (n = 15). RESULTS: Graded BNT162b2 challenge in dual- and PEG mono-allergic patients (n = 3/group) was well tolerated and induced anti-spike IgG seroconversion. PS80 mono-allergic patients (n = 2/2) tolerated single-dose BNT162b2 vaccination. Wb-BAT reactivity to PEG-containing antigens was observed in dual- (n = 3/3) and PEG mono- (n = 2/3), but absent in PS80 mono-allergic patients (n = 0/2). BNT162b2 elicited the highest in vitro reactivity. BNT162b2 reactivity was IgE mediated, complement independent, and inhibited in allo-BAT by preincubation with short PEG motifs, or detergent-induced LNP degradation. PEG-specific IgE was only detectable in dual-allergic (n = 3/3) and PEG mono-allergic (n = 1/6) serum. CONCLUSION: PEG and PS80 cross-reactivity is determined by IgE recognizing short PEG motifs, whereas PS80 mono-allergy is PEG-independent. PS80 skin test positivity in PEG allergics was associated with a severe and persistent phenotype, higher serum PEG-specific IgE levels, and enhanced BAT reactivity. Spherical PEG exposure via LNP enhances BAT sensitivity through increased avidity. All PEG and/or PS80 excipient allergic patients can safely receive SARS-CoV-2 vaccines.

COVID-19 Vaccination Safety and Tolerability in Patients Allegedly at High Risk for Immediate Hypersensitivity Reactions.

The reported incidence of immediate hypersensitivity reactions (IHR) including anaphylaxis after COVID-19 vaccination is 10-fold higher than for other vaccines. Several patient groups are theorized to be at particular risk. Since specific vaccination guidelines for these patients are based on expert opinion, we performed a retrospective monocentric analysis of the tolerability of adenoviral vector and mRNA-based COVID-19 vaccines in a cohort of patients allegedly at high risk of IHR. Reactions were assessed immediately on-site by allergists during a monitored vaccination protocol and after 3-7 days through telephone interviews. The cohort included 196 patients (aged 12-84 years) with primary mast cell disease (pMCD, 50.5%), idiopathic anaphylaxis (IA, 19.9%), hereditary angioedema (HAE, 5.1%) or miscellaneous indications (24.5%). Twenty-five immediate reactions were observed in 221 vaccine doses (11.3%). Most occurred in IA or miscellaneous patients. None fulfilled anaphylaxis criteria and most were mild and self-limiting. Reaction occurrence was significantly associated with female sex. In total, 13.5% of pMCD patients reported mast cell activation-like symptoms within 72 h post-vaccination. All pediatric pMCD patients (n = 9, 12-18 years) tolerated both mRNA-based vaccine doses. In summary, adenoviral vector and mRNA-based COVID-19 vaccines were safe and well-tolerated in patients with pMCD, HAE, and IA. No anaphylaxis was observed. The mild and subjective nature of most reactions suggests a nocebo effect associated with vaccination in a medicalized setting. Patients with pMCD could experience mild flare-ups of mast cell activation-like symptoms, supporting antihistamine premedication.

A double-edged sword.

In medicine, not everything is what it seems and sometimes you need all the pieces of the puzzle in order to complete the diagnosis. This is a case of a disease with two different faces and a review of its respiratory impact. https://bit.ly/2SDKwE5.