Allergy to polyethylene glycol and polysorbates in a patient cohort: Diagnostic work‐up and decision points for vaccination during the COVID‐19 pandemic

Abstract Background During the COVID‐19 pandemic focus has been on polyethylene glycol (PEG) and polysorbate as these excipients are constituents in the first vaccines and possible elicitors of allergic reactions to the vaccines. We aimed to evaluate the possibility of vaccinating patients with PEG and/or polysorbate allergy against COVID‐19. Methods Twenty‐five patients with a history of an allergic reaction to drugs, vaccines and mouth hygiene products containing PEG or polysorbate and sensitization (skin test or in vitro test) or a positive challenge were included. We re‐evaluated 19 of 21 patients diagnosed before 2021 and four new patients by skin prick tests (SPT) and Basophil Histamine Release (BaHR) for PEGs, polysorbates and approved COVID‐19 vaccines as well as measurement of specific IgE (PEG 2000, 10,000). Patients were offered vaccination based on decision points from the primary diagnosis and re‐evaluation. Results Most common primary elicitors were depot‐steroids and laxatives. Most patients had experienced more than one reaction. SPT was superior to BaHR test although many SPTs became negative over time. After careful re‐evaluation three patients were successfully vaccinated with the Pfizer/BioNTech vaccine. Three were vaccinated before referral. Eleven were offered the Johnson‐Johnson vaccine; four were vaccinated successfully, seven abstained. Six patients could not be vaccinated with PEG or polysorbate containing vaccines. Conclusion Hypersensitivity to excipients in COVID‐19 vaccines constitutes a risk to patients with allergy to PEG or polysorbates. After diagnostic evaluation, a safe COVID‐19 vaccine could be offered to most patients, the remainders will await new vaccines containing different excipients.


| INTRODUCTION
In March 2020 the World Health Organization (WHO) declared a pandemic for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)-also called COVID-19. 1 Vaccines were developed with unprecedented speed as a major global preventive measure against COVID-19, and since December 2020 many million doses of various vaccines have been administered globally. In general, severe allergic reactions to vaccines are rare and caused by either the vaccine itself or by excipients contained in the vaccine. [2][3][4] Excipients are necessary to support and optimize the properties of the active ingredients in vaccines, drugs, and other products.
Immediate-type hypersensitivity has been described to several excipients with most reports on polyethylene glycols (PEGs) also called macrogols (E1521) 5 and the structurally related polysorbates. 6 During the COVID-19 epidemic focus has been on these two excipients as they are excipients in the first vaccines on the market in Europe and possible culprits for allergic reactions to the COVID-19 vaccines. [7][8][9][10] Polyethylene glycols are used in pharmaceutical and medical products including vaccines, as well as in cosmetics and industrial and food products. 5 PEGs are polymers of ethylene oxide with molecular weights (MW) ranging from 200 to 35,000 g/mol. In drugs and other pharmaceutical products, the PEG numbers are described by the average MW, but in cosmetics PEGs are described by the average number of ethylene oxide units. 5 Absorption occur through the gastro-intestinal mucosa 11,12 and intact skin 5 depending on MW.
Polyethylene glycol allergic patients may show cross-reactions to PEGylated drugs and structurally similar polymers such as polysorbates and poloxamers. However, the evidence for this still is sparse with only a few cases described. 6,13,14 Polysorbate 80 (E433), also called tween 80, is used in drug formulations including vaccines, as well as in food and cosmetics as a solubilizer, stabilizer or emulsifier. 15  We have recently published results on anaphylactic reactions to COVID-19 vaccines in the normal population and found the incidence to be similar to other virus-based vaccines. 10

| Primary evaluation at diagnosis 2015-2020 (n = 21) and in 2021 (n = 4)
A detailed case history was obtained including comorbidity, suspected culprit drugs/agents and WAO grading of anaphylaxis severity 17 for the first/most severe reaction.
At the primary evaluation SPT to a panel of excipients was performed. SPT was performed with a 1 mm ALK Lancet at the volar surface of the forearm. Histamine solution (10 mg/ml) and saline were used as positive and negative control respectively. 18,19 The size of the resulting wheals was recorded after 15 and 30 min and wheal size was measured on the longest and shortest perpendicular axis, numbers were added and divided by two to obtain the mean wheal diameter. Wheals ≥3 mm larger than the negative control were considered positive. The SPT panel included PEG 300 (100%), 400 (50%), 3000 (50%), 3350 (100%), 6000 (50%), PEG 20,000 (0.01%, 0.1%, 1%, 10%, 20%, stepwise with 30 min interval A Histamine Release (BaHR) test (www.Reflab.dk) was performed using the same allergens as in SPT.
All challenges were performed in a titrated protocol as part of standard operating procedures at the Allergy Center. Movicol ® (PEG 3350) was used as a marker for PEG.  In 2021 the excipient allergy status for each patient was re-classified as certain, possible or unlikely based on primary history, primary testing, the course and re-evaluation and based on this, criteria were made for selection of a safe COVID-19 vaccine whenever possible.

| Ethics
All included patients were registered in the Allergy Center Database, and oral and written informed consent was obtained from all patients. The study was approved by the Danish Data Protection Agency (Journal nr.: 20/63311) and the Ethics Committee (Report nr.: Covid -21/209, nr. 50).

| Primary evaluation at diagnosis 2015-2020 (n = 21) and in 2021 (n = 4)
In total, 25 patients with a diagnosis of PEG allergy and/or polysorbate allergy were included (Table S1), five males and 20 females, mean age at diagnosis 42.4 years (range 19-84 years).
The most common eliciting drugs were depot steroids followed by laxatives (Table S1 and Table 1). More than half of the patients had experienced more than one reaction to drugs, vaccines or mouth hygiene products (14/25). Five patients reacted to new tablets even after the diagnosis had been established (three analgesics, two antidepressants). Seven of the 25 reported local reactions to topical products containing the excipients, all were females (Table S1).
Twenty patients had reactions to drugs, vaccines and consumer products containing PEG, but no history of reactions to polysorbate, while four patients described reactions to both PEG and polysorbate containing products (ID12, ID14, ID16, ID24). The excipient in a depot steroid was unknown in one patient (ID5).
Twelve patients fulfilled the WAO criteria for anaphylaxis for at least one reaction with WAO score 5 in five patients, WAO score 4 in two and WAO score 3 in five. Five patients had a WAO score 2, and eight patients a WAO score 1, of these three experienced delayed reactions with generalized urticaria after 12-24 h.
The diagnostic delay was up to 8 years; however, in 17/25 patients the diagnosis was established within 1 year. Co-morbidity is shown in Table S1.   (Table S1). Furthermore, ID16 diagnosed in 2021 with polysorbate allergy, had a PEG 3350 challenge due to a positive SPT to PEGs without a history of reaction to PEG containing products and PEG challenge was positive.

| Re-evaluation of patients diagnosed 2015-2020 (n = 21; two lost to follow up) in relation to COVID-19 vaccination (2021)
Reproducibility of SPT and BaHR to PEGs and polysorbates over time was assessed in 19 patients diagnosed 2015-2020 and re-tested in 2021.
Twelve patients had a positive SPT to PEGs at the diagnosis. Table 2 shows the reproducibility of SPT over time. At the re-examination, only six (orange in Table 2) of the 12 patients originally testing positive on SPT were positive in 2021. Of the six patients testing negative on SPT two developed urticaria after the SPT (yellow in Table 2), one was BaHR positive (gray in Table 2), while three were both SPT and BaHR negative (white in Table 2). The time between the first and second testing was 1-3 years in those still positive in SPT and 2-6 years in the other groups.
Of the two (ID7, ID11) with negative SPT and BaHR, but a positive oral challenge at the primary evaluation, one had become BaHR positive to polysorbate 80 of unknown relevance, the other reacted with urticaria 1 h after SPT.
All five patients, only positive in BaHR at the primary evaluation, were negative in both SPT and BaHR.

| IgE results in 2021 (n = 23)
Specific IgE (sIgE) to PEG 2000 and 10,000 were measured and were higher than 0.10 kIU/L in four patients for PEG 2000 and in five for PEG 10,000 (Table 3). All four with elevated values for PEG 2000 had positive SPT to PEGs, however, the clinical history varied from mild reactions (ID8, ID10) to moderate (ID18) and severe anaphylaxis (ID12). Table 4 and Figure 1 The allergy status of the patients was re-classified in 2021 as certain, possible and unlikely based on history and disease course, testing on primary evaluation (Table S1) and re-evaluation (Tables 2 and 3). The decision to offer COVID-19 vaccination was made after a risk evaluation based on this information (Table 4, Figure 1).

| Re-evaluation of diagnosis in 2021 and selection of patients for COVID-19 vaccine (n = 23, three already fully vaccinated); see
The four patients with a certain history of both PEG and polysorbate allergy and sensitization to PEG or polysorbate or both were not offered a present COVID-19 vaccination in Denmark [ID12, ID14, ID16 and ID24 (red in Table 3)].
T A B L E 1 Culprit drugs, vaccines and mouth hygiene products at first and subsequent reactions among 25 patients with sensitization or positive challenge to polyethylene glycol and/or polysorbate
Ten patients had a certain PEG allergy but unlikely polysorbate allergy, and were offered a JJ vaccine. Three accepted (ID6, ID7, ID9, green in Table 3) and were successfully vaccinated while seven abstained due to fear of adverse effects (ID1-4, ID11, ID13, ID19, white in Table 3).
After re-evaluation ID21 was classified as possible PEG allergy unlikely polysorbate allergy and was successfully JJ vaccinated (green in -5 of 10 ID23 had unlikely PEG and polysorbate allergy. All three were were offered PB vaccine and vaccinated successfully twice at the Allergy Center (green in Table 3).
Three patients were fully vaccinated before they were referred in 2021 and the decision for re-vaccination in these patients will await the vaccine status at the time of the re-vaccination (blue in Table 3).

| DISCUSSION
There is an urgent need for an allergological work-up program in patients with allergy to PEG and/or polysorbates to make decisions  (Table S1), disease course from diagnosis until retesting and re-testing in 2021 (Table 3). Using risk evaluation criteria based on the gathered information (Table 4)     another Danish study where re-exposure reactions mainly were elicited by everyday cosmetic products used on the skin and with mild reactions as also found in our patient group. 14 Is it unknown why more women than males (20/25) were identified in our cohort. However, one possible explanation could be that the primary sensitization occur through the skin and women are in generally more exposed to topical products than males. However, it is unknown if the primary sensitization is through the  The immunological mechanisms in PEG anaphylaxis are not clear but an IgE mediated mechanism has been suggested. [26][27][28] Specific IgEs to PEG 2000 were higher than 0.10 in four patients (

ACKNOWLEDGMENT
Thank you to Bjarne Kristensen from Thermo Fisher Scientific for performing the specific IgE analyses.