Protocol of safe vaccination against COVID-19 in patients with high risk of allergic reactions

Background Sars-CoV-2 infections are hazardous, especially to the elderly and patients with comorbidities. With no efficient treatment available, newly developed vaccines are the only way to change the course of the pandemic. However, reports of allergic reactions resulted in some patients and practicing physicians being concerned about the safety of vaccine administration, particularly in people with severe anaphylactic reactions to multiple or unknown factors in their medical history. This study aimed to develop an allergic work-up protocol based on skin prick tests (SPT), intradermal testing (IDT) and intramuscular provocations, and desensitisation which may contribute to diagnosis and management of anti-COVID-19 vaccine allergy. Methods Two hundred and eighty-five patients were enrolled. Two hundred and five of them entered the study based on severe anaphylactic reaction to unknown or multiple factors in their medical history which disqualified them for standard treatment. Another 80 patients were enrolled after developing an allergic reaction to the first dose of one such vaccine. In all subjects, SPT and IDT were performed. Serum tryptase was assessed in 79 patients randomly chosen from the study group. Results Two hundred and seventy-seven patients with negative tests were given a vaccine without complications. Seven patients had positive skin tests. In two cases, tests confirmed Comirnaty allergy, while the other five confirmed solely skin sensitisation with no exposure prior to the study. Six patients with positive tests received titrated challenge using desensitisation protocol with a reasonable tolerance. One patient did not consent to desensitisation and one patient resigned despite negative tests. Overall, 283 (99%) patients were vaccinated using this newly developed protocol. Patients with adverse reactions to the first dose of the vaccine before the study had a significantly lower basal serum tryptase concentration (p = 0.001). Conclusion Skin tests with anti-COVID-19 vaccines are a useful tool in the vaccination protocol. This protocol enables safe immunisation of high-allergy-risk patients even in cases of positive skin tests.