key: cord-0024326-5nsr65i0 authors: Troeltzsch, Matthias; Berndt, Ronald; Troeltzsch, Markus title: Comment on “Oral lichen planus following the administration of vector based COVID‐19 vaccine (Ad26.COV2.S)”. Authors' reply date: 2021-11-10 journal: Oral Dis DOI: 10.1111/odi.14060 sha: bddd7b5511a317e80bc1e8b2a164bd793df1a20c doc_id: 24326 cord_uid: 5nsr65i0 nan Dear Editor, We would like to respond to the comment of Mungmunpuntipantip and Wiwanitkit (Mungmunpuntipantip & Wiwanitkit, 2021) to our letter entitled "Oral lichen planus following the administration of vector based COVID-19 vaccine (Ad26.COV2.S)" (Troeltzsch et al., 2021) . It has to be highlighted that the occurrence of oral lichen planus (OLP) in timely association with the COVID-19 vaccination (Mungmunpuntipantip & Wiwanitkit, 2021) . The evidence for this theory is very limited but it might serve as an additional, underestimated factor in the etiology of OLP. There is a significant risk of OLP development in patients suffering from chronic Hepatitis C (Gill et al., 2016) . In those patients, both diffuse immune system activation and an increase of blood viscosity due to mixed cryoglobinemia are observed (Gill et al., 2016) . Further research will be warranted to further explore the exact underlying mechanisms. The aim of our letter to the editor was to encourage the scientific community to screen patients presenting with (extensive) OLP lesions for a possible timely association with a COVID-19 vaccination to increase the body of knowledge in this field. Ad26.COV2.S, COVID vaccine, COVID-19, oral lichen planus The corresponding author would like to thank Prof. Dr. Dr. Michael Ehrenfeld (Professor and Department Chair, Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital, LMU, Munich) for his mentorship. None declared. Durable Humoral and Cellular Immune Responses 8 Months after Ad26.COV2.S Vaccination Hepatitis C virus as a systemic disease: reaching beyond the liver COVID-19 and Lichen planus Oral lichen planus: an update on its pathogenesis Oral lichen planus following the administration of vector-based COVID-19 vaccine (Ad26.COV2.S). Oral diseases