Infektionsgeschehen ab 2017
Im Winterhalbjahr 2016/17 erhöhte sich die Anzahl der Infizierten besonders stark: Bis Mitte Februar 2017 wurden insgesamt 1223 Erkrankte registriert, von denen 380 verstorben waren; allein zwischen dem 17. Januar und dem 14. Februar hatte es in China 305 neue Erkrankungen gegeben, mindestens 79 Erkrankte starben im Januar 2017 an den Folgen der Infektion. Im März 2017 wurde A/H7N9 erstmals in den USA nachgewiesen; im Rahmen von Routinekontrollen in einem Geflügelzuchtbetrieb in Tennessee wurde eine LPAI-Variante entdeckt, was zur Tötung von 16.500 Masthähnchen führte.
Am 15. Juni 2017 waren der WHO insgesamt 1533 bestätigte Infizierte bekannt, von denen mindestens 592 Personen verstorben waren, am 27. September 2017 berichtete die WHO über 1564 bestätigte Infizierte, von denen laut China National Health and Family Planning Commission 612 Personen verstorben waren. Bis zum 28. Mai 2018 erhöhte sich die der WHO bekannte Fallzahl geringfügig auf 1567, davon 615 Todesfälle, und bis zum 25. November 2019 auf 1568 Erkrankungen.
Other large influenza pandemics
The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic. Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.12 Estimates for the death toll of the “Asian Flu” (1957-1958) vary between 1.5 and 4 million. Gatherer (2009)13 published the estimate of 1.5 million, while Michaelis et al. (2009) published an estimate of 2–4 million.14 According to a WHO publication the “Hong Kong Flu” (1968-1969) killed between 1 and 4 million people.15 Michaelis et al. (2009) published a lower estimate of 1–2 million.16 The Russian Flu pandemic of 1977-78 was caused by the same H1N1 virus that caused the Spanish flu. According to Michaelis et al. (2009) around 700,000 died worldwide.17 What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history.
How the Spanish flu differs from the Coronavirus outbreak in 2020
Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of COVID-19 compares. When comparing COVID-19 with the Spanish flu, there are a number of important differences that should be considered: They are not the same disease and the virus causing these diseases are very different. The virus that causes COVID-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above. The age-specific mortality seems to be very different. As we’ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes COVID-19 appears to be most lethal to the elderly, based on early evidence in China. We’ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past. But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time. Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary bacterial infections. Morens et al (2008) found that during the Spanish flu “the majority of deaths … likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory–tract bacteria.” And not just health systems were different, but also the health and living conditions of the global population. The 1918 hit a world population of which a very large share was extremely poor – large shares of the population were undernourished, in most parts of the world the populations lived in very poor health, and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent large shares of their resources on the war. While most of the world is much richer and healthier now, the concern today too is that it is the poorest people that are going to be hit hardest by the COVID-19 outbreak.
These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago.