Quarantine for the sick is an age-old method. Lockdowns of entire populations for extended periods is a massive experiment, and the closest analogy we have is the wholesale internment of Japanese Americans in WWII, based on the idea that some of them might pose a danger.
> Weekly deaths per 100,000 from 1918 pandemic above the expected rate.
The 1918 with worst cities 400+ Weekly deaths per 100.000 people are not comparable with the following numbers of COVID-19. Note that covid numbers not weekly but total.
> The Johns Hopkins University looked into the number deaths per 100,000 of the population in the top-10 countries worst affected by COVID-19. Belgium had over 57,000 cases on May 25 but it had the highest number of deaths per 100,000 of its inhabitants at 81.53. By comparison, badly-hit Spain and Italy had 57.43 and 55.64 deaths per 100,000 people respectively. The U.S. has surpassed 1.5 million cases and its deaths per 100,000 inhabitants stood at 30.02 on May 25.
> The quarantine against chol era has been lifted in the Black Sea port of Odessa, Pravda re ported today, but Soviet travel organizations said they were still limiting travel to the city.
From the New York Times archive, 1970 [1]. The Soviet government quarantined Odessa in 1970 during the cholera outbreak in a rather cruel way - information about the outbreak was suppressed but since it was a popular vacation spot, people kept coming only to be trapped there [2]. It's hard to find much information on the event due to the iron curtain but I've heard several personal accounts and the similarities are striking.