COVID-19 vaccination and immunoreactant deposition in non-autoimmune oral mucosal pathologies

Coronavirus disease 2019 (COVID-19), resulting from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), led to nearly 7 million deaths reported worldwide. Vaccines, known to reduce mortality, were granted emergency use authorization by the U.S. Food and Drug Administration, including BNT162b2 (Pfizer-BioNTech, 2 doses), mRNA-1273 (Moderna, 2 doses), and JNJ-78436735 (Janssen, 1 dose). During the time of vaccine rollout, a peculiar histopathologic finding was noted in oral mucosal tissue samples: basement membrane zone immunostaining, particularly with anti-complement C3 in patients with no autoim-mune disease. This study aimed to investigate a possible temporal link between COVID-19 vaccination and deposition of immu-noreactants in oral mucosal tissue samples, retrospectively.

Biopsy reports (n = 142) were reviewed for patients aged 16 years or older who underwent a medically necessary incisional oral tissue biopsy with direct immunofluorescence staining. Vaccination status was confirmed through patient vaccination cards.

Of the 27 cases where the non-specific immunostaining was present, 25 (92.6%) were obtained from patients who had previously received vaccination, yielding an OR of 7.068 (95% CI, 1.712-31.27; Fischer's exact test P = 0.0042).

Although the significance of the immunoreactant deposition remains unknown, this study pro-vides a foundation for further exploration of oral mucosal immunity associated with COVID-19 vaccination and possibly other vaccines.