Second-dose COVID-19 vaccines are well tolerated in patients with allergic reactions to the first dose - a single center experience.

COVID-19 vaccines contain additives such as Polyethylenglycol-2000 (PEG2000; mRNA vaccines) or Polysorbat 80 (vector vaccines), which have been described previously as culprits for anaphylactic events. This retrospective study included 46 individuals, who were referred to Comprehensive Allergy Center at the Department Dermatology and Venereology, Kepler University Hospital, Linz, Austria, with suspected allergic reactions to the first COVID-19 vaccine dose with either mRNA or vector-based vaccines. Patients underwent detailed anamnesis, clinical examination, and in most cases, skin prick testing using pure additive substances (PEG - different molecular weights, Polysorbate 80). Out of 46, 7 patients' reactions were classified as possibly anaphylactic and graded according to Ring & Messmer. Forty patients out of 46 were assessed with skin prick tests for potential allergens in COVID-19 vaccines. Only 1 patient showed an immediate positive prick test to PEG2000. Second-dose vaccination with mRNA or vector-based vaccines were tolerated well in all patients, including the individual with a positive skin prick test against PEG2000. The currently available COVID-19 vaccines have an overall low allergic potential and may be administered safely in patients with suspected allergic reactions to the first dose.