Photodynamic inactivation of influenza virus as a potential alternative for the control of respiratory tract infections

Over the last centuries, the influenza virus has been the cause of one of the deadliest and most concerning respiratory tract infections. Besides being annually responsible for thousands of deaths worldwide, it's capable of originating pandemics that can affect millions of people, like COVID-19. Photodynamic inactivation (PDI) is an emerging alternative solution for the treatment and control of viral infections and several studies have already shown that it can be efficient against influenza viruses. Herein we give a brief overview of key biological and epidemiological features of influenza and some insights on how to guide the development of new techniques for the management of influenza. This is followed by a review of in vitro and in vivo assays that have been carried out so far for the photodynamic inactivation of different influenza strains, using different families of photosensitizers (i.e. porphyrins, phthalocyanines, phenothiazinium dyes and analogues, among others) with diverse molecular size and charge (neutral, anionic or cationic). Finally, we give a brief perspective and update on the potential nasal inactivation of COVID-19 using PDI.