The 1918–1919 Spanish influenza pandemic killed more than 50 million people around the world that included 675,000 Americans.
The initial and sustained imposition of bans on mass gatherings, school closures, and other social-distancing measures significantly reduced mortality rates during the 1918–1919 epidemics.
The second wave occurred during the fall of 1918 and was the most severe that caused the majority of the United States deaths. By the end of September 1918, more than 14,000 flu cases were reported at Camp Devens equaling about one-quarter of the total camp, resulting in 757 deaths. The 1918 flu pandemic virus has killed an estimated 195,000 Americans during October alone, which is about 28% of all United States deaths. However, the exact death toll and case fatality rate of the second wave is unknown because of inadequate and incomplete records.