Viral reactivation following COVID-19 vaccination: a review of the current literature.

Currently, four vaccines for COVID-19 have been licensed by the European Medicines Agency: two viral vector-based vaccines and two mRNA-based vaccines. 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. The aim of this article was to investigate the current literature regarding viral reactivations following COVID-19 vaccination, focusing attention on pityriasis rosea (PR), herpes zoster and herpes simplex. A comprehensive literature search using various databases was performed and we included metanalyses, reviews, letters to the editor, real-life studies, case series and reports. A total of 48 articles involving 2067 patients were selected. Of these, 32, 6 and 17 articles reported varicella zoster virus (VZV) reactivation (1758 patients), herpes simplex virus (HSV) (238 patients) onset and PR (71 patients), respectively (some articles discussed more than one of these three reactivations). Possible pathogenetic mechanisms underlying viral reactivation are still not understood. Also, the possible correlations between vaccination and viral reactivation should be clarified. Certainly, vaccination should not be discouraged.