A BBC documentary called "The Flu That Killed 50 Million" is informative. As of time 130 million were infected and 200 thousand dead, Sir Arthur Newsholme, senior medical officer at Whitehall, sent a message to his European counterparts proposing a cease fire because an existential threat to humanity transcends national rivalries. (Just kidding!) He actually decided against even warning the public to take any precautions because it would not be "expedient" for the munitions factories to slow down. My takeaway is never to put it past those in power to decimate of the population if it suits their ends.