BCG Scar Local Skin Inflammation as a Novel Reaction Following mRNA COVID-19 Vaccines in Two International Healthcare Workers.

Bacillus Calmette-Guérin (BCG) local scar inflammatory reactions have been mostly associated with Kawasaki disease in children and less commonly with other viral infections (i.e., measles). BCG scar inflammation associated with or following vaccine administration has only been reported with the influenza vaccine. We describe the first reports in the literature of local BCG inflammation following two different available messenger ribonucleic acid (mRNA) anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) vaccines (mRNA-1273, and BNT162b2) in two young healthy physicians, one from Costa Rica, and another from the United States of America, with normal cell blood counts, flow cytometries, and negative for human immunodeficiency virus (HIV). In both cases, BCG scar inflammation appeared after 24 hours of vaccination of the second dose, without signs of reaction on the injection site, and resolved within four days. Dermoscopic findings in one case showed arborizing and comma-shaped vessels. Pharmacovigilance surveillance of BCG scar reactions following coronavirus disease 2019 (COVID-19) vaccines should be considered particularly in countries where BCG is part of their national immunization programs.