"No one really knows how many people died, but the first contemporary estimates put deaths at 21 million worldwide. That estimate is often still quoted, but it was certainly far worse than that. MacFarlane Burnett spent much of his life studying influenza, and he concluded that the worldwide death toll (from the 1918–1919 pandemic) was a minimum of 50 million, possibly 100 million. He may well have been right. If you adjust for population, that could be 300 million today. In three weeks, it killed more people than AIDS has in 24 years. In the U.S., a reasonable estimate starts at 500,000 deaths. Personally, I am inclined toward a higher estimate of 700,000. There was 15–53% morbidity. In San Antonio, over 90% of households had at least one family member with the illness. Most of the deaths occurred in healthy adults. In Army camps, the death toll was routinely over 5%, sometimes as much as 10%, and in some communities as high as 30%."