Intradermal fractional dose vaccination as a method to vaccinate individuals with suspected allergy to mRNA COVID-19 vaccines.

Suspected allergic reactions after mRNA COVID-19 vaccination withheld multiple individuals from getting fully vaccinated during the pandemic. We vaccinated adults who had experienced possible allergic symptoms after their first intramuscular dose of a COVID-19 mRNA vaccine with a 1/5th fractional intradermal test dose of the mRNA-1273 (Moderna) COVID-19 vaccine. No anaphylactic reactions were observed after intradermal vaccination (n = 56). Serum anti-S1 IgG concentrations were measured using a bead-based multiplex assay four weeks after vaccinations. Antibody concentrations were compared with a previously collected nationwide cohort that had received two intramuscular doses of mRNA-1273. Antibody responses in all subjects tested (n = 47) were comparable to standard of care intramuscular dosing. Fractional intradermal dosing of mRNA COVID-19 vaccines may provide a pragmatic solution that is safe, time efficient compared to skin prick testing, dose sparing and immunogenic in individuals with suspected vaccine allergy.