How does Coronavirus (Covid-19) compare to Spanish flu?

How does Coronavirus (Covid-19) compare to Spanish flu?

In Health, Videos by Paul ShillitoLeave a Comment


There is a saying that goes along the lines of, “the man that looks to the past and future is blind in one eye but the man that looks the future only is blind in both”. Although this is something which we should heed at all times, in the case of the coronavirus its particularly relevant because with the advantage of hindsight we can see where we made big mistakes in the past either from just sheer lack of knowledge at the time or from a belief that covering things up for whatever reason will somehow make it less of an issue, something which continues in places around the world today.

So with the biggest worldwide response to a pandemic in a 100 years, how does the coronavirus Covid-19 compare to last truly global pandemic of Spanish flu from 1918 to 1920.


Now even with the worldwide concern over the coronavirus, there will still be people out there saying that seasonal flu kills far more people, up to 650,000 worldwide every year, which is true and we aren’t making a fuss about that. But that to coin a phrase, that’s because is one of the known unknowns, we know it will happen every year and we are prepared for though some years are worse than others.

When something like Covid-19 comes pretty much right out of the blue and into a population with no immunity, it’s highly contagious and has a death rate of a least 20 times that of flu, then we have the makings of a major problem, especially with cheap air travel around the world, it can spread faster now than it ever could have done in the past.

As we have seen in China, Italy and now other countries, a large sudden spike in cases requiring hospitalisation can almost crash even the best health services, not to mention the associated economic damage of the shutdown required to contain the outbreak which in all probability will push the world into a recession.  So reacting quickly with the best practices at the time becomes essential and even though the virus cant be stopped everywhere, the worst effects can hopefully be mitigated.

We haven’t seen a major pandemic in living memory, there have been many more localised epidemics involving various strains of flu, other coronaviruses including SARS and MERS both of which are more deadly than Covid-19 and the deadliest of them all Ebola.

We have to go back just over 100 years to 1918 to see the worlds last truly global pandemic. If we exclude the bubonic plague of the middle ages, Spanish Flu as came to be known as the worst health crisis in recorded history infecting about 30% of the then world population of 1.8 billion people and killing somewhere between 17 to 50 million all around the world. This stands as a solemn reminder of what can happen when a pandemic gets truly out of control.

Of course, the circumstances were very different, when the Spanish flu pandemic struck in 1918 world war 1  still raging and there was only a very rudimental knowledge of the viruses and the diseases they caused.

We now know that Spanish flu was an outbreak of the H1N1 influenza virus, a type of virus that is common in birds and mammals like pigs which is why it is sometimes called bird flu or swine flu. It’s believed to have jumped the species gap through close contact with infected animals in the food chain.

Its exact beginnings are unknown, some believe that it originated in China and then mutated at a US military camp in Kansas before being spread to a British army hospital in France and on to the frontline. Others say that it had been circulating in European armies for maybe a year or more before being first noted at the British army hospital in 1918.

Whichever way it occurred, from there on and after the war ended, soldiers returning to their home countries spread the infection to rest of Europe, the US and British empire countries before it eventually it spread to every inhabited continent in the world. Even in the wilds of Alaska and islands in the middle of the Pacific there were recorded deaths due to Spanish flu.

But this is where things are different to the current coronavirus or Covid-19. First of all the two viruses are not the same, Spanish flu is an influenza virus and Covid-19 is a coronavirus genetically related to, but not the same as the SARS virus of 2002-2003, so it is not a flu virus even though some of the symptoms are quite similar.

Although the common cold is also a coronavirus, it is much much less potent than these newly emergent zoonotic viruses like MERS, SARS and now Covid-19. These have jumped from animals to humans in a very short space of time and because of this, we have no natural or built-up immunity to them.

The problem is that in about 80% of Covid-19 cases the symptoms are mild and with many people facing financial hardship due to the measures taken to counter the outbreak there could be a fair number of them will still at work or out and about ready to spread the virus. This means that the other 20% will need some sort of care or hospitalization and if a large number become infected it becomes a numbers game with far more people than there are beds or ventilators available, which what we are now seeing with all the knock-on effects for other people in the health system.  

Back in 1918, the coinciding of the outbreak of Spanish flu with the last year of the war was also instrumental in the spread of the disease as news about it was suppressed by the US, British, French and Germans for fear that it might compromise moral and show weakness to the enemy which could then be exploited militarily. Spain was neutral during the war and had no restrictions on the reporting of the outbreak and thus it came to be known as Spanish Flu simply because they were the only ones reporting it openly. This suppression of information allowed it to spread far more quickly than it would have if more people knew about it.

At the time the general health and hygiene of much of the population was much lower than it is now. The was much more poverty and malnutrition especially in Germany which had been blockaded by the British Navy since the beginning of the war and by 1918 this was causing major hardship to the German people with shortages of fuel and food.

These alone lead to a dramatic increase in diseases caused by malnutrition such as scurvy, tuberculosis and dysentery and also added to the increased likelihood of people becoming infected with the flu due to weakened immune systems.

Although Spanish flu and Covid-19 are different viruses they both attack the lungs in a much more aggressive way than seasonal flu.

Spanish Flu was also different to seasonal flu because it affected normally fit people in their 20-40’s, the age range of the average soldier in the war rather than the very young and old of normal flu.

In many of the fatalities, what is now known as a “cytokine storm” occurred. This is where the bodies own immune system and its activating compounds, the cytokines, flood the lungs instead of just the areas where the virus is located. The result is that lungs damaged by the immune system leading much greater inflammation and fluid build-up and allowing secondary bacterial pneumonia to take hold.

Now, Covid-19 is said to affect mostly the old and those with underlying health issues with data from china showing very few children under 14 being seriously affected but doesn’t mean that younger people from the age of 15 to 50 people aren’t as likely to be severely affected by it.

Covid-19 is also more contagious than flu with each Covid-19 suffer infecting 2 to 3 others were as the seasonal flu suffer infects only about 1.3 new people.

Information from Italy and China is showing that in the most serious cases of Covid-19, the virus attacks the lungs aggressively creating a large amount of inflammation and fluid build-up leading to secondary bacterial pneumonia, X-rays of severe Covid-19 cases often show almost completely white lungs.

It has also been found that the virus attacks the heart directly meaning that anyone with a heart problem whether they know about it or not is also at greater risk of a heart attack as well as severely reduced lung function.

The “cytokine storms” that were the major killers in Spanish Flu are also common in the worst cases of Covid-19 and if left untreated are usually fatal. Fortunately over the last two decades and since SARS, much has been learned about how to diagnose and treat “cytokine storms” but it requires medical professionals to be aware of it and identify it.

Those which have survived the worse infection of Covid-19 are often found to have been left with lung damage from both the scaring of the virus its self and the overreaction of the immune system.

This brings us on the mortality rate, for Spanish flu it appears to have been around 2.5% compared to normal flu of about 0.1%, that’s about 25 times more deadly.

In a report from the Chinese Center for Disease Control and Prevention, a link is in the description, which looked at 42,672 confirmed cases, it found the mortality from Covid-19 was 2.3% or roughly similar to Spanish Flu. This means that Covid-19 is 23 times more lethal than seasonal flu. This 2.3% mortality rate was across all ages of 15 upwards but above 80 it climbs to 14.8%.

As to who gets seriously ill and who don’t depend on how the individual reacts to the virus rather than what age they are. A fit old person with no health issues might have a mild infection, were as an unfit younger person with health problems could be seriously ill. The figures are skewed for the over 80s because they are far more likely to will have underlying health issues.

So how did the Spanish flu outbreak end, well it didn’t just fade away after the initial wave, a second much deadly mutation spread in France, the US and Sierra Leone, a British protectorate at the time.

Its thought that during the initial wave, civilians who fell seriously ill stayed indoors and those with a milder form carried on in normal life spreading the milder form of flu.

However, for the soldiers the opposite was true. Those with the mild version stayed at the front whilst those with the most severe form were sent back taking the more deadly mutation with them to spread it in the hospitals and to other new troops arriving.

This is something that virologists look out for in outbreaks today for today because if a virus reaches places were there is large scale social upheaval there is a greater chance for a more deadly mutant strain to develop.

In the end Spanish flu peaked in Oct 1918 with cases dropping off abruptly in the following month though it’s spread carried on more slowly around the world till 1920. The reason for this is believed that the most severe form killed many of those infected and thus it died with them. Another common occurrence is that Flu virus often mutates rapidly becoming less lethal in the process.

We still don’t know how Covid-19 will react or mutate in the long run and that even after containment measures are ended that it won’t bounce back with even greater severity, we will only know this in the fullness of time.

Over the years since WW1 much more emphasis was placed on the casualties of the war than Spanish Flu and the deadliest pandemic since the bubonic plague and that probably killed many more people than the war itself was mostly forgotten about.

More recently since the outbreak of SARS and MERS, the far more deadly forms of the coronavirus, there has been a new interest in how and why Spanish flu spread so widely and was so deadly, so as to understand what might happen in the future.

It’s been said that many times that a new global pandemic was a matter when rather than if.

We live a world that that is interconnected in ways which would have been unimaginable back in 1918 with far better knowledge and ability to fight the virus so it’s almost impossible that the results would be the same but this is still going to poses the biggest health crisis with all the knock-on effects that we have seen in our lifetimes.

Paul Shillito
Creator and presenter of Curious Droid Youtube channel and website

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.