1918-1920 Spanish flu killed estimated 50 million In a world population of 1.8 billion Makes it a .027% killer
In a time when there were no efficient international travel except by boat.
Zero draconian measures
COVID has killed 2,440,000 In a world population is 7,800,000,000 Makes it a .0003% of the population killer
Even though we have international travel exponentially higher than in 1920 COVID kills at .01% of the Spanish flu per capita yet we destroyed our way of life , our economy, our kids future
That's less a flaw and more an attempt at stopping what we know. There's a prediction game involved with this stuff.
A vaccine does not(and cannot), generally, cover all strains of a disease. This is why there are new vaccines each year.