Syndemic
The worst of the 20th century influenza pandemics was the 1918 pandemic, where between 20-40 percent of the world’s population became ill between 40-100 million people died. More people died of the so-called Spanish flu (caused by the H1N1 viral strain) pandemic in the single year of 1918 than during all four-years of the Black Death. The pandemic had devastating effects as disease spread along trade and shipping routes and other corridors of human movement until it had circled the globe. InIndia, the mortality rate reached 50 per 1,000 population. Arriving during the closing phase of the World War I, the pandemic impacted mobilized national armies. Half of U.S. soldiers who died in the "Great War," for example, were victims of influenza. It is estimated that almost ¾ of a million Americans died during the pandemic. In part, the death toll during the pandemic was caused by viral pneumonia characterized by extensive bleeding in the lungs resulting in suffocation. Many victims died within 48 hours of the appearance of the first symptom. It was not uncommon for people who appeared to be quite healthy in the morning to have died by sunset. Among those who survived the first several days, however, many died of secondary bacterial pneumonia. It has been argued that countless numbers of those who expired quickly from the disease were co-infected with tuberculosis, which would explain the notable plummet in TB cases after 1918.
German casualties in World War II
Statistics for German World War II military casualties are divergent and contradictory. The wartime military casualty figures compiled by German High Command, up until January 31, 1945, are often cited by military historians when covering individual campaigns in the war. A recent study by the German historian Rüdiger Overmans found that the German High Command statistics are not reliable, he estimated German military dead at 5.3 million, including 900,000 men conscripted from outside of Germany's 1937 borders, in Austria and in east-central Europe. The German government still maintains that its records list 4.3 million dead and missing military personnel. Civilian deaths during the war include air raid deaths, estimates of German civilians killed only by Allied strategic bombing have ranged from around 350,000 to 500,000.
Civilian deaths, due to the flight and expulsion of Germans and the forced labor of Germans in the Soviet Union are disputed and range from 500,000 to over 2.0 million. According to the German government "Suchdienste" (Search Service) there were 300,000 German victims (including Jews) of Nazi racial, political and religious persecution. This statistic does not include 200,000 German people with disabilities who were murdered in the Action T4 and  Action 14f13 euthanasia programs.