The five years of “Spanish Lady” influenza (this is from the Gina Kolata book) shows that the 1916 season saw the start of it, 1918 was the peak, and the trailing years were ‘19 and ‘20. There was something peculiar about that particular strain, as those who were about to die hemorrhaged in their lungs.
Another Kolata find, those who had survived the worst flu strain of the 1890s already had immunity from the Spanish Lady, never even got the sniffles.
The reason so much effort is put into annual innoc’s for flu is to keep the mortality down. In the US, over the ten years from 2010 to 2020, the lowest was in 2011-2012 (12,000) and the worst two (2014-15, 2017-18) around 50,000 fatalities. Average is somewhere around 30,000 a year in the US, and worldwide estimates range from 294,000-518,000.
I’ll go way out on a limb here and suggest that the US, with perhaps 5 percent of the world’s population, has a much better system of dealing with influenza than most of the world, so that these world figures suffer from severe underreporting. It wouldn’t surprise me to learn that A) annual worldwide flu fatalities are north of a million, or B) that geography, jet stream, human travel etc tend to disproportionately funnel the bug into North America from its Chinese reservoir/homeland.
Ebola (the bad outbreak in West Africa happened 2013/4–2016, when the Kenyan-born muzzie was in office), and (it sez here) less than a dozen in the US were treated for it, and two died. Worldwide, something like 11K died, mostly in western Africa.
They only called it the "Spanish Flu", because as a neutral during WWI, Spain was one of the few countries that didn't censor reports of cases in their country, thus the only reports people heard about were the cases in Spain. There is speculation that there were so many cases in Germany, it was a factor in them losing the war.