Alopecia Areata after COVID-19 Vaccines.

Introduction: Alopecia areata (AA) is a common autoimmune disease characterized by non-scarring hair loss. New onsets of AA have been associated with coronavirus disease 2019 (COVID-19). Various skin diseases have already been reported because of the vaccines (the Pfizer-BioNTech COVID-19 vaccine, the Moderna COVID-19 vaccine, the AstraZeneca vaccine) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Case presentation: We report 5 cases of AA after COVID-19 vaccination. The trend shown by patients in this study is an initial worsening after the first dose of the vaccine with the stability of the disease even with subsequent doses. However, it is worth highlighting the case reported by one of our patients who suffered a "booster effect" of the disease with progressive and worsening alopecia with each vaccine booster.

Discussion: The possible mechanism of action lies in the ability of COVID-19 vaccines to induce spike protein, which can lead to molecular mimicry phenomena. In an organism predisposed to autoimmunity, the mRNA vaccine acts as a trigger. Furthermore, we would like to point out how even cytokine storm and simple oxidative stress from SARS-CoV-2 infection can induce not only AA but also other types of hair loss such as telogen effluvium. Thus, this highlights how complex and multifaceted the phenomenon is.