A little over a century ago the most lethal epidemic in human history began. It was caused by a virulent form of the H1N1 influenza-A virus. It’s origin is uncertain. Originally thought to have first appeared in Kansas, it may even have originated in China. Regardless of where it started it rapidly spread throughout the world. It lethality, initially mild, increased such that a person could be healthy in the morning and dead from this flu in the evening.
Unlike other respiratory viruses, this one disproportionately affected young people. The reason older people were relatively spared is theorized to be the result of residual immunity caused by previous infections with less lethal strains of the virus a generation or two earlier.
That the world was at war explains the early infection of soldiers and sailors housed in close quarters and subsequently transported all over the US and then the world. The Wilson administration obsessing exclusively on the war effort essentially ignored and then denied the nationwide epidemic. Having assumed dictatorial powers the federal government forced the press and local officials to play down the seriousness of this plague.
The fourth and final wave of the disease occurred in 1920. New York City was hard hit during this wave as were a number of other US cities as well as other countries. Then it was gone.
The disease may have infected as many as 500 million people, about 30% of the world’s population at the time. There were between 10 to 50 million deaths. Thus, most cases were not lethal, but a mortality rate approaching 10% is substantial and terrifying to those who lived through the pandemic. Of course, the true number of infected people may have much larger as those with minimal or no symptoms were not counted. Underestimating the real number of infections would cause the mortality rate to be lower than thought, though it was high enough regardless of its real rate.
The high death rate has often been attributed to secondary bacterial infections. Given the nature of the fatal cases of the disease and the rapidity of death, secondary infection seem unlikely to be the main culprit in patients who died soon after the onset of the disease. In addition to its rapidity, death was associated with extreme cyanosis, hemoptysis, bleeding from the mouth, ears, and even eyes. On post mortem examination the lungs were consolidated. Almost every organ was affected in addition to the lungs. All this suggests a cytokine storm brought on by an overly vigorous immune response. Remember, most of the deaths were in healthy young people who had intact immune systems. Deaths that occured well after the onset of the flu likely were due to secondary bacteria infections.
Why did the disease vanish? Some degree of herd immunity is possible. Also likely, is that successive passages of the virus through multiple human hosts attenuated it such that its virulence decreased as did its ease of spread. No treatment worked. Masks were used, but it’s hard to tell if they were effective in preventing spread of the virus, though anecdotal evidence suggests they might have helped. Lockdowns and closures were applied after the virus has been spread round the world. While military doctors and other health professionals did what little they could to stem the avalanche of deadly pneumonia, the US government, as mentioned above, did virtually nothing to prepare the public or ease the impact of the disease.
The best depiction of the flu pandemic known to me is The Great Influenza by the historian John M Barry. Though his depiction of the disease’s gory details is sometimes a bit breathless and while he often confuses symptoms with signs, even writing about symptoms noted on autopsy, he give a vivid account of the disease, its effects, its four waves, and the key players who struggled with little success against the outbreaks. Barry starts the book with a concise history of medicine beginning with Hippocrates. His picture of 20th century medical science falling back to therapies that doctors knew were ineffective is still pertinent. Doing nothing, even when it’s the best course, is always next to impossible. The therapeutic imperative is more powerful than a speeding bullet.
The current COVID-19 pandemic is far less serious than was its predecessor of a century ago. Thus far less than 1% of the world’s population has been infected. The 1.2 million deaths currently attributed to the virus is much lower, even in absolute terms, than that of the 20th century influenza pandemic. The current number is likely is an overestimate as anybody dying with a positive test for the virus, irrespective of underlying morbidity, is counted as a death from the coronavirus.
Another major difference between the two infections is the age distribution. The coronavirus afflicts older people while leaving the young and healthy virtually unscathed. This pattern is exactly the opposite of the 1918-20 situation. The largest number of deaths were in people in their twenties and early thirties. Pregnant women were the hardest hit demographic.
The government during the earlier epidemic largely did nothing. President Wilson, as mentioned above, was manically fixated on the war. Intervention when the disease was first recognized in servicemen might have stopped the spread to civilians and other parts of the world. One can’t be sure that early intervention would have had a great impact, but it’s a real possibility.
The nature of the current milder infection strongly suggests a nuanced approach. Unfortunately, many state governments have opted for lockdowns. The only justification for such a course is to prevent hospitals from being overwhelmed. Older individuals and those with compromised immune systems can stay sequestered while younger and healthier people go about their ordinary business. Alas, many states have opted for a overly muscular approach, one which batters the constitution in addition to causing injury both economic and medical
Many needed health interventions are being delayed both out of fear on the part of patients from interacting with the medical apparatus and from the disproportionate diversion of medical resources to fight the virus. Getting things right and proportionate during a crisis is not a human strong suit.
At least on the surface, it seems that we’re doing now is what we should have done a century ago and vice versa. In 1918-20 many clinicians did not successfully identify the epidemic as a virulent strain of influenza. Many other diagnoses were considered. Today we understand more than enough to mount an assault against the new virus that is effective and which doesn’t cause more harm than good.
Looking back also provides a picture of what a really serious pandemic looks like. Another will certainly appear before too long. We should take two lessons from The Great Flu. First, be prepared for the worst – new and serious infectious diseases are a recurring fact of life. Second, when the infection does appear, do a risk benefit analysis before and during whatever course of prevention and treatment is decreed.