TABLE 2 Patients with PEG allergy and polysorbate allergy/possible polysorbate allergy ID Elicitor WAO grade Positive SPT (primary evaluation, re-evaluation) Positive BaHR (primary evaluation, re-evaluation) Specific IgE (PEG 2000/10,000) Challenge PEG 3350 Primary vaccine offered Secondary vaccine offered Result of vaccination 12–38 M Movicol laxative (PEG 3350) Infliximab (polysorbate 80) ×2 WAO 5 DMG-PEG 2000, PEG 3350, PEG 6000, PEG 20,000 (0.01%), Polysorbate 80 - 0.11/0.63 ND None Comirnaty® divided in four doses Successfully vaccinated ×2 14–31 F Moxaxole laxative (PEG 3350) Brintellix (PEG 400) WAO 2 PEG 2000, DMG-PEG 2000, PEG 3350, PEG 6000, PEG 20,000 (0.01%), Poloxamer 407, Polysorbate 20, Polysorbate 80 - <0.10 ND None Comirnaty® divided in four doses Successfully vaccinated ×3 16–19 F Vaxzevria® vaccine (polysorbat 80) Movicol laxative (PEG 3350) WAO 1 PEG 300, PEG 2000, DMG-PEG 2000, PEG 3000, PEG 6000, PEG 20,000 (0.1%), Poloxamer 407, Polysorbate 20, Polysorbate 80, Spikevax®, Vaxzevria® Spikevax®, Vaxzevria®, Comirnaty® <0.10 Positive None Comirnaty® divided in four doses (Omalizumab treatment—CSU) Successfully vaccinated ×2 18–22 F Primcillin (PEG 6000) Depo-Medrol steroid injection (PEG 3350) WAO 3 PEG 2000, DMG-PEG 2000, PEG 3000, PEG 3350, PEG 6000, PEG 20,000 (0.01%), Poloxamer 407, Polysorbat 80, Polysorbat 20 Poloxamer 407, Comirnaty®, Spikevax® 1.24/2.11 ND None Comirnaty® divided in four doses Successfully vaccinated ×2 10–47 F Depo-Medrol steroid injection (PEG 3350) WAO 1 DMG-PEG 2000, ALC-PEG 2000, PEG 6000, PEG 20,000 (0.1%), Poloxamer 407, Polysorbate 80 DMG-PEG 2000, ALC-PEG 2000, Comirnaty®, Spikevax® 0.27/0.53 ND Comirnaty® ×2 before referral Comirnaty® divided in four doses Successfully re-vaccinated ×1 8–50 F Diprospan steroid injection (PEG 3350) Movicol laxative (PEG 3350) Vagifem (PEG 6000) WAO 1 PEG 2000, DMG-PEG 2000, PEG 3000, PEG 3350, PEG 6000, PEG 20,000 (0.01%), Poloxamer 407, Polysorbat 80 PEG 20,000 (10%), Comirnaty®, Spikevax® 22.70/39.10 ND None Comirnaty® divided in four doses Abstained Anaphylaxis to PEG is rare. 1 Most reactions described in the literature are elicited by depot-steroid injections and laxatives. 1,2 In relation to COVID-19 mRNA vaccines, PEG was identified as a possible elicitor in case of anaphylaxis, since modified PEG 2000 are used as excipient in mRNA vaccines. 3,4 Polysorbate 80 is used in viral vector vaccines and a potential cross-reactivity between PEG and polysorbate has been hypothesized, 2 due to structural relationship. Why these PEG allergic patients tolerated the vaccine with modified PEG 2000 may be explained by the patients individual threshold in relation to the small amount of PEG in the mRNA vaccine, the lower molecular weight of PEG 2000 compared to higher molecular weight PEGs in for example, laxatives and depot-steroids (PEG 3350), or the conjugation with lipid-nanoparticles in mRNA vaccines. 11,12 Titrated vaccination has been described in PEG allergic patients. CONFLICTS OF INTEREST The authors report no potential conflict of interest.