How does the coronavirus compare to the Spanish flu?

The coronavirus crisis inevitably prompts comparisons with the last epidemic that shook the world: the Spanish flu. Although the Great War overshadowed it in the public consciousness, this outbreak killed at least 30 million people worldwide – with some estimates even putting the figure at 100 million from 1918 to 1919. But are the two epidemics really comparable?

As the coronavirus outbreak accelerated after first emerging in the Chinese city Wuhan at the end of 2019, there have been more comparisons with the Spanish flu a century ago.

“People are talking about the Spanish flu right now because at the time, it was shocking; the biggest health crisis the world had ever known in terms of how it affected the demographic balance,” noted Anne Rasmussen, a historian at the EHESS university in Paris. “Of course, there was the Black Death [which caused between 25 and 34 million deaths in Europe from 1347 to 1353], but the Spanish flu was on a much more global scale.”

“But at the same time, the Spanish flu and the coronavirus are not really comparable,” Rasmussen continued. “Things are completely different today. One has to be very careful to avoid using comparisons that create more fear than illumination.”

Two very different diseases

Although the two diseases are both respiratory infections with common symptoms such as a runny nose and fever, they belong to different families of viruses. “Pneumonia and pleurisy caused a lot of death in 1918; people were suffocated – they felt like they were drowning,” said Rasmussen. “With regard to the coronavirus, France’s director general for health Jérôme Salomon emphasised how different it is from the influeneza virus; the clinical profile, the severity, the biological signs are all different.”

The coronavirus is also more threatening to very different age groups from those who were hit hardest by the Spanish flu. The former affects the elderly and those with pre-existing medical conditions most severely. By contrast, the latter was most deadly for young adults – a rare phenomenon that continues to intrigue epidemologists.

“We’re still trying to explain it, especially seeing as we now have the decoded DNA of the 1918 virus,” Rasmussen said. “One factor that may help explain it is that the flu had already circulated over previous decades, particularly during the 1889 epidemic. People who were alive at that point could have found themselves to be partially immunised when the Spanish flu broke out three decades later.”

Another fundamental difference lies in the level of knowledge about the two diseases, Rasmussen said: “At the time of the Spanish flu, people didn’t know the influnenza pathogen, and without this knowledge, it wasn’t possible for them to create a vaccine. They knew they were dealing with a flu and that it was contagious, but they weren’t able to see the viruses because they were too small. That subsequently became possible with the electron microscope.”

Scientists did not isolate the particular virus strain that causes influenza in humans until 1933. Of course, scientific knowledge is much more advanced today. “We decrypted the RNA of the coronavirus within a few days, whereas for HIV/AIDS it took a few years,” Rasmussen said.

‘Let’s not create more fear’

The Spanish flu killed more people in 24 weeks than HIV/AIDS killed in 24 years, hitting countries ravaged by the Great War as it accelerated to become an epidemic. It acquired its name not because it originated in Spain – there is not enough epistemological data to definitively pinpoint its place of origin – but because the Spanish media were relatively free to report it in a neutral country, unencumbered by the censorship present in combatant nations.

The disease spread like wildfire in overcrowded army camps and hospitals, then spread to the rest of the world after raging through Europe. Patients did not benefit from modern resuscitation techniques or the antibiotics necessary to treat the complications the disease caused.

There was a divergent range of responses to the epidemic. In France, where the Spanish flu killed 240,000 people, there were bans on some gatherings and some public places were closed – but nothing like the current coronavirus lockdown. The focus was on the war effort.

“They were going through the final stages of the war, with decisive moments in a series of offensives and counter-offensives,” Rasmussen said. “You couldn’t stop people moving around because that would have hindered military operations.”

Despite the terrifying scale of the Spanish flu, it was not until 1948 that the World Health Organization was founded to co-ordinate the prevention and detection of disease outbreaks on a global scale. There were several outbreaks in the ensuing decades: the 1957 Singapore flu, the Hong Kong flu in 1968 and H1N1 in 2009.

“We learned a lot of lessons from each of these epidemics, with a much more efficient monitoring system – and we’re even better prepared today,” Rasmussen said. “Let’s not create more fear; the current state of affairs already provokes enough anxiety. It’s a different world now from the one that saw the Spanish flu. Things are done on a different scale now, with much more research and a much more efficient approach to dealing with diseases. There are great reasons for hope.”

Photo: Sisters during Spanish Flu 1918 (National Museum of Australia)

This article was adapted from the original in French.