A comprehensive review of oral microenvironment changes and orofacial adverse reactions after COVID-19 vaccination: The good, the bad, and the ugly.

BACKGROUND AND AIMS: Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have the potential to alter several biological systems concurrently with remolding the immune system, most of which are related to immunization, while some others are known as adverse effects. This review aims to explore the potential effects of vaccination on the oral microenvironment and classifies them as good, bad, or ugly, with a brief review of facial diseases following coronavirus disease 2019 (COVID-19) vaccination.

METHODS: This study was a comprehensive review conducted through searching related articles in Medline, Scopus, and Google Scholar databases.

RESULTS: On one side, the "Good" impacts of vaccination on the oro-nasal mucosa are explained as if the mucosal immune responses followed by SARS-CoV-2 vaccines are enough to provide immunity. On the other side, the possible "Bad" and "Ugly" effects of the vaccine, which manifest as orofacial adverse events and autoimmune reactivations, respectively, should be noted. Exacerbation of pre-existing autoimmune conditions such as lichen planus, pemphigus vulgaris, bullous pemphigoid, and Stevens-Johnson syndrome have been reported.

CONCLUSION: COVID-19 vaccines could affect different biological systems alongside stimulating the immune system, and some of these effects are referred to as adverse effects. Nonetheless, these adverse effects are treatable, and healthcare professionals should not prevent patients from taking the first available vaccination.