"Besides replicating very quickly, the 1918 strain seems to trigger a particularly intense response from the immune system, including a ‘cytokine storm’ – the rapid release of immune cells and inflammatory molecules.
Although a robust immune response should help us fight infection, an over-reaction of this kind can overload the body, leading to severe inflammation and a build-up of fluid in the lungs that could increase the chance of secondary infections.
The cytokine storm might help to explain why young, healthy adults – who normally find it easier to shake off flu – were the worst affected, since in this case their stronger immune systems created an even more severe cytokine storm."
BBC, Why the Flu of 1918 Was So Deadly
Behind the concrete, the visible events, behind all the objective, logical considerations, we find the struggle against evil, against the servants of the antichrist. Everywhere and always demonic powers lurk in the dark, waiting for the moment when man is weak. When he yields to the forces of evil, he separates himself from the power of a higher order; after taking the first step, he is driven on and on to the next and to the next, at a furiously accelerating rate.
Die Weiße Rose, 1942