[A study on the 1946 smallpox epidemic in Japan and measures taken against it].

In early 1946, immediately after World War II, there was a smallpox epidemic in Japan. In this paper we investigated trends in the occurrence of smallpox by week and region using official documents of the General Headquarters, Supreme Commander for the Allied Powers (GHQ/SCAP), which are stored in the National Diet Library Modern Japanese Political History Materials Room, and summarized the measures taken against this epidemic. The following two points were clarified: 1) The 1946 smallpox epidemic peaked in Week 13 (March 24-30; 1,405 new patients), and the highest morbidity during this epidemic was seen in Hyogo Prefecture, followed by Osaka Prefecture, Aichi Prefecture, Tokyo Prefecture, and Hokkaido Prefecture. 2) Measures taken against this epidemic were classified into the following three stages: 1. "Vaccine shortage/Manufacture acceleration stage," 2. "Vaccine sufficiency/Smallpox vaccination program implementation stage," and 3. "Detection of defects in vaccination technique/Reimplementation of the smallpox vaccination program stage".