It is important to understand a risk as deeply as possible, and it is important to learn from other similar events or incidents. However, sometimes people stop when they think they have reached a simple, believable conclusion.
It appears that COVID-19 hits older people worse than others, perhaps because they are less resilient or because they are more likely to have underlying medical conditions.
It is also known that the Spanish flu epidemic of 1918-19 hit those between 20 and 40 hardest; and it was thought that this was perhaps because older people had had more time to acquire immunity. Another suggestion is that more potent immune systems in the young overreacted to the virus, triggering a dangerous and sometimes fatal immune reaction known as a cytokine storm. Something like this is already being noted in 20%-30% of Covid-19 fatalities in China and in the US without being able to tell why immune cells in these cases are attacking the lungs they should be protecting.
Researchers may have stopped investigating Spanish flu once they were satisfied that it simply hit the young harder than the old. However, a demographer at the University of Montreal has been studying the data for years and discovered that within the 20-40 age group, there was a big spike in fatalities at age 28, undermining the idea that it was simply a young v. old thing. A hypothesis developed by Australian and American army doctors suggests that in some circumstances, early exposure to a virus can harm a later immune response rather than help it, and experiments on pigs have apparently shown that early exposure to one virus can result in later, different viruses having a more severe impact than they otherwise might.
Now 28 years before Spanish flu, there was a pandemic of Russian flu – a different and less lethal strain. It is possible that the immune systems of newborns exposed to Russian flu may have learned about Russian flu too well, so that when, 28 years later they were exposed to Spanish flu, they gave the wrong response.
And it seems that people born in 1918 suffered more in the Hong Kong flu epidemic of 1968; and those born in 1957 during the Asian flu epidemic showed higher mortality when confronted with swine flu. So maybe there is more going on here in the way the virus works and how it affects people differently.
This is an unproven hypothesis still, but it highlights that one’s immediate understanding of a risk or issue may not be all that there is to it.
Data Sources:The Economist magazine, www.knowablemagazine.org