5. The disease spread across the globe with astonishing speed
There is little doubt that the disease which came to be known as Spanish Flu was aided in its spread by the First World War, which offered the conditions in Europe which favored the spread of contagious illness of any kind. But its simultaneous eruption across the globe defied explanation other than that it was transmitted by the global shipments of men and materials. The disease would likely have spread with the same speed had the war not been underway, but it may have been less deadly, as it would not have found men massed together in unhealthy environments. Where populations were largest, densely packed, the disease was at its deadliest.
In heavily populated India the Spanish Flu killed up to 17 million people, approximately 5% of the total population of the subcontinent. The areas of the Indian subcontinent under the control of the British Raj – the most densely populated region – saw just under 14 million dead. Throughout the rest of India, the total number of dead can only be estimated, it may have been much higher. It was during the second wave of the pandemic, which began in August 1918 and hit its peak, in terms of fatalities, in October of that year that the flu seemed to differ from other strains of flu. Until then it had followed the usual pattern of most fatalities being the elderly and infirm, and young children. In the autumn of 1918 Spanish Flu began to kill a disproportionate number of young men.