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

Coronavirus disease-2019 (COVID-19) has significantly hampered the regular workflow for allergists and allergy departments.

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.

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.

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.