[thinker912345]

The H1N1 flu spread during the first world war that humanity has ever had. It came in waves and each wave was evolved. Talk about extremely unique circumstances to brew the perfect storm.

When COVID-19 spread, there was literally nothing different occuring at the time that could have provoked any evolutionary changes in any virus to be more evolved in infecting humans outside of normal human density levels.

Flu viruses have been evolving in humans for millenia. This has not.

[dehrmann]

> there was literally nothing different occuring at the time that could have provoked any evolutionary changes in any virus to be more evolved in infecting humans outside of normal human density levels.

There is now, though. We're selecting strains that aren't as concerned with masks and social distancing. Back in March, I remember reading some anecdotal accounts of cities' responses to H1N1, but it wasn't widespread. We've never actually stopped somethings this widespread, so it's not clear how these measures play out long-term.

[CryptoPunk]

To expand on your first point, the circumstances of World War 1 led to carriers of the asymptomatic strains of H1N1 staying in place, in trenches, where the strains extinguished themselves for lack of hosts to spread to.

Carriers of the more symptomatic strains were transported to military hospitals which acted as conduits of transmission.

The result was the virus progressively evolving to become more deadly.

The first wave of the Spanish flu had a fatality rate that is typical of the flu, with deaths preponderantly amongst the elderly, which again is typical.

The second wave was massively more deadly, and killed the young in large numbers.

Source: https://en.wikipedia.org/wiki/Spanish_flu#Transmission_and_m...