Earlier quoted context omitted.
It's worth noting that the 1918 flu was unique in that it killed many young, healthy people. Corona virus is more typical in that it's primarily killing the very old or otherwise ill. https://www.worldometers.info/coronavirus/coronavirus-age-se...
How much of that was down to the disease, compared to the conditions that "young, healthy" people would have been subjected to during a world war?
"Why did so many young adults die? As it happens, young adults have the strongest immune systems, which attacked the virus with every weapon possible—including chemicals called cytokines and other microbe-fighting toxins—and the battlefield was the lung. These “cytokine storms” further damaged the patient’s own tissue."
The more robust immune response was a large cause of the increased mortality.