Photos show how San Francisco emerged from a lockdown too soon during the 1918 Spanish flu pandemic, leading to an even deadlier second wave that rampaged through the city

• San Francisco received national praise for its early, proactive response to the Spanish flu pandemic in the fall of 1918.
• But when the number of cases tapered off by November 1918, the city relaxed restrictions on the public too early, ultimately leaving San Francisco with one of the highest death rates in the US by the spring of 1919.
• As another pandemic grips the city a century later, San Francisco's past decision-making could provide the best guidance for sheltered-in-place residents on keeping the coronavirus disease at bay: be patient.
• Visit Business Insider's homepage for more stories.

During the fall of 1918, the city of San Francisco acted quickly when the Spanish influenza hit, implementing a shutdown and enforcing mask-wearing in public.

If that sounds familiar, it's because San Francisco is one of many Bay Area counties that also took proactive steps in combating the COVID-19 pandemic in 2020. But if San Francisco's track record of responding to pandemics is any indication, lifting the gates on the lockdown too soon could have disastrous consequences.

Spanish flu infections seemed to dwindle by November 1918, and the city relaxed lockdown orders. When another wave hit San Francisco, much of the public — including "The Anti-Mask League" — resisted the mandates that city leaders re-enacted to help blunt the spread of the disease. The city ended up with nearly 45,000 cases and over 3,000 reported deaths.

It's a cautionary tale as officials across the US fight to "flatten the curve" against the coronavirus disease by implementing stay-at-home orders and city shutdowns, even as some Americans protest those measures.

Here's how San Francisco went from serving as a national role model to having one of the country's highest death rates during the Spanish flu pandemic of 1918 and 1919.