BTW I got the flu vaccine one year and still got the flu. But a dose of Tamiflu and I was fine in a couple of days. The people I knew who rode it out had problems for months.
Note; In the Spring of 1918, the Spanish Flu appeared but it wasn’t fatal and died off when flu season ended. When the Fall flu season began, it wiped out entire villages.
This is the book I am reading now. It’s kinda wonky but good.
Flu : the story of the great influenza pandemic of 1918 and the search for the virus that caused it / Gina Kolata.