SARS-CoV-2 and allergy - what have we learned after two and a half years?

BACKGROUND: Coronavirus disease-2019 (COVID-19) has significantly hampered the regular workflow for allergists and allergy departments. MATERIALS AND METHODS: The purpose of this review is to highlight our own experiences on SARS-CoV-2 and allergy as well as to discuss findings from the literature. RESULTS: Vaccination against SARS-CoV-2 is needed for protection against severe infection. Skin reactions may arise with SARS-CoV-2 infections. Short-term general immune reactions and skin reactions are also possible upon SARS-CoV-2 vaccination; however, they recur in only a proportion of patients during follow-up vaccinations. Initial reports of anaphylaxis after vaccination fueled public fear. On the other hand, more recent epidemiologic data do not show a substantially increased anaphylaxis risk compared with other vaccines. Fear-related reactions may be essential for many "anaphylaxis" reports. In Germany, the flow chart developed by Paul-Ehrlich-Institut (PEI) and Robert-Koch-Institut (RKI) together with the allergological societies helps to care for patients with suspected "allergy history" safely and effectively. Through this, patients with increased risk of anaphylaxis to SARS-CoV-2 vaccines and their ingredients (e.g., polyethylene glycol (PEG), polysorbate 80) are identified. However, since only small amounts of these excipients are contained in mRNA vaccines, even some PEG-allergic patients can tolerate the vaccination. In Germany, an allergy test-guided procedure is recommended for high-risk patients, including an allergy history, prick tests, intradermal and basophil activation tests, and, if necessary, provocation tests. This also appears effective for anxiety reduction in patients with vaccination skepticism. To date, all of our patients have been able to be vaccinated with SARS-CoV-2 vaccines without the occurrence of significant reactions. CONCLUSION: Many initial concerns about unexpected side effects of SARS-CoV-2 vaccination have not been confirmed. The flowchart and, in the case of suspicion of hypersensitivity, an allergy test-guided risk assessment helps to reduce patients' fear of vaccination and enables safe vaccination.

Cutaneous reactions following COVID-19 vaccination assessed by dermatologists: a single-institutional study in Germany.

BACKGROUND AND OBJECTIVES: Cutaneous reactions following COVID-19 vaccination have been frequently described, whereas larger case series by dermatologists are lacking. This study assesses SARS-CoV-2 vaccination-associated skin reactions, severity, treatment, course, eliciting vaccines, allergy test results and tolerance to revaccination. PATIENTS AND METHODS: Single-institutional, non-interventional study of dermatologists assessing cutaneous manifestations in 83 patients in Germany. RESULTS: 93 reactions were presented. Manifestations clustered into immediate (n = 51, 54.8%) and delayed hypersensitivity reactions (n = 10, 10.8%), chronic inflammatory skin diseases (n = 13, 14.0%), reactivation of latent herpes virus infection (pityriasis rosea/herpes zoster; n = 9; 9.7%) and others (n = 10, 10.8%). Vaccination was associated with new (76.3%) - mostly hypersensitivity reactions - or exacerbation of known skin diseases (23.7%), in this case predominantly chronic inflammatory skin diseases. Reactions occurred primarily within the first week (72.8%) and after first vaccination (62.0%). Treatment was required in 83.9% and hospitalization in 19.4%. In 48.8% revaccination led to recurrence of the same reactions. Disease was ongoing at last consultation in 22.6%, primarily in chronic inflammatory skin diseases. Allergy tests were performed in 15 patients (18.1%) and resulted negative. CONCLUSIONS: It can be assumed that vaccination may trigger immune activation-related reactions especially in those patients predisposed to develop respective skin diseases.

Do basophil activation tests help elucidate allergic reactions to the ingredients in COVID-19 vaccines?

The worldwide use of COVID-19 vaccines has shown that immediate allergic reactions to the ingredients are rare but should be clarified by means of an allergological work-up. This review aims to highlight the current state of knowledge and possible pathogenesis based on the literature published to date. In addition to recording a detailed history and performing skin tests, cellular tests (basophil activation or basophil histamine release test) by using the vaccines or modified compounds containing polyethylene glycol (PEG), rather than unmodified PEGs, have proven to be particularly helpful. Negative results with vaccines seem to indicate tolerance. Details of the performance of these cellular tests with different vaccines, PEGs of different molecular weights, other ingredients of the vaccines, as well as other PEGylated drugs, and the results in the context of COVID-19 vaccination of various working groups worldwide are summarized.

Experience with polyethylene glycol allergy-guided risk management for COVID-19 vaccine anaphylaxis.

BACKGROUND: Polyethylene glycol (PEG) may elicit anaphylaxis to COVID-19 mRNA vaccines, and guidance for patients at risk is needed. METHODS: In retrospective patients with PEG allergy collected from 2006 till 2019, clinical, skin, and basophil activation test (BAT) characteristics discriminative for PEG allergy were analyzed and compared with the literature. In 421 prospective real-life patients asking for allergy workup for COVID-19 vaccine hypersensitivity in 2020/2021, risk assessment was performed and tolerance of the recommended vaccination approach was assessed. RESULTS: Ten patients with PEG allergy were found in the retrospective cohort. Patients reacted with immediate anaphylaxis (100%) not only to PEG-based laxatives/bowel preparations or injections, but also to cold medication, antiseptics, analgetics, or antibiotics. Skin tests ± BAT with PEG ± elicitors were positive in 10/10. Provocation tests were positive in 7/9 patients. From the prospective cohort, 370/421 patients self-reporting increased risk for vaccine allergy lacked criteria necessitating allergy workup and were recommended for routine vaccination. A total of 51/421 patients were tested, and three (6%) with PEG allergy were identified, whereas 48 patients remained negative in skin tests. Vaccination was recommended in all those patients. No hypersensitivity reactions were reported to vaccination including six PEG-allergic patients tolerating COVID-19 vaccination. CONCLUSIONS: Taking a detailed history excluded PEG allergy in most referred patients and enabled direct safe vaccination. Immediate urticaria/anaphylaxis to typical elicitors identified patients requiring PEG allergy workup. Skin tests ± BAT identified PEG allergy and helped to select the vaccine and the vaccination approach. Even PEG-allergic patients can tolerate COVID-19 vaccines.