“…The clinical course of post-vaccine SHL can be variable, from unilateral forms to bilateral forms with an involvement that can be partial, severe and often permanent [3,4,13,25,26]. However, it is not always possible to verify to association; in a study in 2016 Baxter et al [27] analyzed all cases from 2007 to 2013 of first SHL diagnosis in a specific time interval from the administration of vaccines against tetanus, pertussis, diphtheria, varicella and inactivated influenza trivalent and did not find any significant evidence correlating the two events.…”