Following the Japanese invasion in Singapore, several healthcare policies were put in place by the new occupying forces. Concern for the spread of diseases prompted the Japanese government to implement a system of compulsory vaccination against smallpox and typhus in April 1942. Those who were inoculated were issued with certificates as proofs of their vaccination. In 1943, the pre-war Medical Department and Sanitary Boards were replaced by a new department created by the Japanese, called the Eiseika.
