Bacillus Calmette-Guerin Site Reaction After COVID-19 mRNA Vaccination

The document discusses a series of 5 cases where individuals experienced Bacillus Calmette-Guerin (BCG) site reactions following COVID-19 mRNA vaccination with Pfizer-BioNTech. The patients, aged between 22 and 49, developed erythematous reactions at the BCG scar site, which were temporary and resolved spontaneously within a few days. The study suggests that these reactions may be due to passive stimulation of memory T cells or molecular mimicry involving lipid nanoparticles in the vaccine. The authors conclude that BCG site reactions post-vaccination are likely under-reported but are generally mild and self-limiting.