In the early 20th century, when Spanish flu and tuberculosis were prevalent, laborers in the Japanese textile industry worked long hours in poor conditions, and the risk of contracting an infectious disease was high. In such a situation, forward-thinking companies set up hospitals as a voluntary measure for dealing with infectious disease, provided free medical care and assistance payments in the event of illness, improved company dormitories, and introduced other measures for safeguarding workers’ welfare such as upgrading factories and offering educational programs. These programs influenced other companies and resulted in improvements in the working conditions at a number of firms, indicating that these countermeasures against infectious diseases were economically rational. This in turn implies that it is economically rational to upgrade sanitation and workers’ welfare in response to the current COVID-19 pandemic.