Not so. The 1918 influenza when it first started infecting people it was bad, but many recovered. But when the US troops fighting in Europe started coming home, they brought back with them a much deadlier strain, the 2nd wave. By they 3rd and 4th waves the virus had weakened but that was little comfort to the families of the estimated 500,000 who died.
The Origin and Virulence of the 1918 “Spanish” Influenza Virus
Not necessarily.