In the 1st century CE, Emperor Tiberius made an unprecedented decision: banning kissing at all public events. This move was aimed at thwarting a puzzling outbreak, which many historians believe was an epidemic of oral herpes. Today, more than half the population is infected with herpes simplex virus. So, what causes herpes? And how can we treat it? Christine Johnston examines this stealthy virus. Lesson by Christine Johnston, directed by Igor Ćorić, Artrake Studio.