Background Suspected allergic reactions to the 1st dose of the coronavirus disease 2019 (COVID-19) mRNA vaccines have been reported to be as high as 2%, with anaphylaxis up to 2.5 per 10000 individuals. Anaphylaxis to the 1st dose may be considered a contraindication to administration of the 2nd dose, necessary for optimal protection against severe disease. Many individuals with anaphylactic reactions to the 1st dose still want to receive a 2nd dose. However, there is little published data to support the administration of a 2nd dose safely in this population. Objective The primary outcome for this study was determining the percentage of patients tolerating the 2nd COVID-19 mRNA vaccine dose after an immediate reaction to the 1st dose. Methods This was a retrospective chart review of 47 patients at a Canadian hospital who had immediate, suspected allergic reactions following their 1st COVID-19 mRNA vaccine dose and received a 2nd dose within our allergy clinic. For detailed Methods, please see the Methods section in this article's Online Repository at www.jacionline.org Results 46 of 47 patients tolerated the 2nd dose. 43% of patients developed mild, transient symptoms. There were no patients who developed anaphylaxis or needed epinephrine after the 2nd dose. Conclusion Our case series adds to current evidence that administration of a 2nd COVID-19 mRNA vaccine dose has a good safety profile in patients with a history of immediate reactions after the 1st dose, including those with a history of anaphylaxis to the 1st dose.
Second dose mRNA COVID-19 vaccine safety in patients with immediate reactions after the first dose: A case series.