Taxanes hypersensitivity is not a risk factor for severe reactions to SARS-CoV-2 vaccines

Background. Hypersensitivity reactions (HSR) to taxanes have been related to a complement activation by their excipients, polyoxyethylated castor oil and Polysorbate 80, structurally related to those of SARS-CoV-2 vaccines. The aim of this study was to verify the presence of a higher risk of HSR to SARS-CoV-2 vaccines in patients with history of HSR to taxanes. Methods. Patients with history of HSR to taxanes were evaluated before the vaccination in our center and underwent skin tests for PEG and Polysorbate 80 (PandP). Some patients completed the vaccination course in other centers without prior PandP skin tests because they had not manifested taxanes hypersensitivity before vaccination, or because those tests were not available. Results. 50 patients were evaluated. 100% of patients with history of hypersensitivity to taxanes completed the vaccine course with no cases of anaphylaxis. 33 underwent skin tests for PandP before the vaccination and no correlation was found between the positivity of PandP and taxanes skin tests (p = 0.538). 7 patients developed mild symptoms during skin tests and vaccination, similar but weaker than those suffered at the time of the taxane infusion, independently from the results of skin tests. Conclusions. In our cohort patients with history of reaction to taxanes were not at higher risk to develop anaphylaxis to SARS-CoV-2 vaccines. However, a common non-IgE mediated mechanism behind those HSRs cannot be completely excluded. This can only account for mild and harmless symptoms in case of SARS-CoV-2 vaccines. However, prudence is still recommended in these patients.