I was under the impression that the Spanish flu was very different from the regular flu and COVID-19, because it was the young/old people that survived it and the healthy 20-50 year old that died the most. Most people died of the Spanish Flu because of their immune response. It looks like COVID-19 is really mild* for lots of people in that age group.
Am I missing something? Did the Spanish flu start like COVID-19 and evolved later?
The flu regularly migrates between pigs, chickens and humans. Whenever it does, the poorly adapted flu is unusually lethal.
The misnamed Spanish flu seems to have killed by triggering a strong immune response. That response is called a cytokine storm. Which means that the stronger your immune system, the more likely you were to be hit hard. It therefore killed the reverse of the groups that normally get killed by diseases.
There is also some evidence that people who experienced the "Russian flu" of 1889-1890 had some level of protection from the Spanish flu.
Primarily death was due to bacterial pneumonia, the cytokine storm likely accelerating the deterioration of the lungs. That particularly viral strain may have been more dangerous, but overall the current pandemic is comparable in death rates.
It would seem during the Spanish flu your best chance of survival was being in a location where strict quarantine and travel restrictions were imposed so the health system was able to cope with those who did contract the virus.
The places with the highest fatality rates were those with poor or non-existent health services or where people didn't seek medical assistance.
The mortality rate in the US was around 0.5%, <1% in East Asia, but 5% in India and as high as 20% in some Pacific nations. Iran's current Covid-19 mortality rate is quite comparable to the Spanish Flu around 14%.
I.e 5x deadlier than the seasonal flu TODAY with an approx 0.1% mortality rate in the US, which has been decreasing steadily, so perhaps only 2-3x deadlier than the normal seasonal flu today on average.
"In 1918, doctors lacked intensive care units, respirators, antiviral agents, and antibiotics, an important fact in light of historical evidence of interactions between influenza and secondary bacterial respiratory pathogens (e.g., Haemophilus influenzae) as a significant cause of death during the pandemic." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2374803/
Yes, the book says the 1918 flu hit healthy robust people the hardest. There are many other differences. For example, that flu had a super short incubation time, so it swept through communities in 7 weeks, and military bases in 4-5. On many bases thousands could become ill in a single day. It's spread was much more rapid.
But there are lots of other similarities as well: Hospitals were rapidly overwhelmed. With both flu and coronavirus, it is the pneumonia that is dangerous (also, apparently true of measles). Some people died very quickly of their own immune response and massive lung damage (SARDs, severe acute respiratory distress) while others succumbed later to secondary bacterial pneumonia. Health authorities were reluctant to acknowledge the problem for fear of creating panic. Many people and communities attempted to self-isolate, with very limited success.
There are some possible similarities that have not yet played out - notably multiple waves of infection with different mortalities and characteristics.
Overall, the book has a lot of detailed scientific explanations that I enjoyed. One of my favorite parts was a detailed explanation of the significance of "H" and "N" in flu names (e.g. H1N1), and why flu mutates so rapidly, and is so likely to cross over in certain animals. Overall, I recommend it if you like detailed but comprehensible scientific explanations.
> corona: "crown" (from latin corōna, meaning "crown")
> virus: "poisonous secretion" (from latin vīrus, meaning "venom" or "poisonous secretion")
> Coronavirus, the virus responsible for 30% of common colds, as well as SARS, has the appearance of a crown (corona) under electron microscopy, due to the spike proteins that coat the viral surface. Viruses, being so small, might have been thought of before they were discovered, to be poisonous secretions (virus) of unknown origin, hence their name.
It is unrelated but the mechanism by which the association came about is funny: it was first widely (read: honestly) reported by Spain, therefore everyone associated it with Spain, even thought first cases, including initial deaths, were in other countries which suppressed the news.
Am I missing something? Did the Spanish flu start like COVID-19 and evolved later?