Viral Reactivation Following COVID-19 Vaccination: a review of the current literature

Background: Currently, four vaccines for COVID-19 have been licensed by the European Medi-cines Agency: viral vector-based vaccines (AstraZeneca; AZD1222 and Johnson & Johnson; Ad26.COV2. and 2 mRNA-based vaccines (Pfizer/BioNTech; BNT162b2 and Moderna; mRNA-1273). Since their approval, several cutaneous reactions related to vaccination have been reported in the literature. Among these, viral reactivations are one of the most frequent. Objectives: The aim of this manuscript was to investigate current literature regarding viral reactivations following COVID-19 vaccination, focusing the attention on Pityriasis Rosea, Herpes Zoster and Herpes Simplex. Methods: A comprehensive literature research using various databases, including metanalyses, re-views, letters to the editor, real-life studies, case series, and reports, was performed. Results: A total of 47 articles involving about 2000 patients were selected. Of these, 32, 6 and 17 articles reported VZV reactivation (1,758 cases), HSV (238 cases) onset and PR (71 cases), respectively. Conculsion: Possible pathogenetic mechanisms underlying viral reactivation are not still understood as well as the possible correlations between vaccination and viral reactivation should be clarified. Certainly, vaccination should not be discouraged.