The 1917-1918 flu pandemic also stood out for the many novel short-term and long-term effects, most of which we are still learning about because records and data collection were so poor. Every new spillover is an opportunity to learn what can happen that was not captured in our very bad memory of such events, effectively none of which have been rigorously recorded until the mid-20th century.

There is, in other words, no reason to suspect any particular outcome. Given how poorly we handled the still-ongoing SARS-CoV-2 pandemic there is zero reason for optimism.