**5. Clinical implications and future perspectives**

Until the successful development of the first Covid-19 vaccine in December 2020, one of the greatest challenges in fighting the disease was the lack of specific medication and vaccination. To this end, epigenetic mechanisms have been considered as promising targets for novel therapeutic approaches due to the important role of epigenetic regulation during viral infections including viruses of the *Coronaviridae* family. Several epigenetic modifier enzymes such as DNMTs, HATs, HDACs, HMTs and KDMs are proposed as candidate targets for the treatment of Covid-19. For instance, histone demethylase KDM5B could be targeted for the prevention of Covid-19 as its inhibition stimulates interferon production and provides resistance to viral infections [84]. Targeting epigenetic modifiers could open up a new revenue for the inhibitors against these enzymes, which are already in the market for therapeutic purposes, as potential antiviral agents to be used in drug repurposing attempts. In line with this, Decitabine, an inhibitor of DNA methylation (NCT04482621) and Dipyridamole, an inhibitor of NET formation (NCT04391179) are currently in clinical trials for Covid-19 therapy [28, 114]. Other clinical trials based on epigenetic markers aim to study microRNAs and DNA methylation patterns in relation to Covid-19 (NCT04403386 and NCT04411563) [28].

In conclusion, it is critical to characterize the molecular pathways that take part in SARS-CoV-2 infections to the best of our knowledge to have a better understanding of Covid-19 and to develop better therapies and vaccines for treatment. Epigenetic regulation machineries are involved in several virus-related cellular processes, suggesting epigenetic factors as promising targets for therapy. In this book chapter, we provided a comprehensive overview of epigenetic mechanisms in viral infections with a special focus on SARS-CoV-2 infection, which we believe will be useful for future studies.
