This NHK video report says the epidemics of previous periods in history were no different than today. It points to the Nara period (710-794) when smallpox killed 20 to 30% of the population. This was a period of international exchange and large roads were built bringing people from all parts of Japan to Nara and increasing the risk of infection. In fact the Great Buddha at Nara was built by the Emperor at the time to entrust the peace of Japan to the Buddha.
Original article 1 minute, gist 1 minute