This article on COVID-19 is very helpful:
The 2006 Origins of the Lockdown Idea by Jeffrey A. Tucker | May 15, 2020
A high school student’s computer simulation study in 2006 was adopted by the Bush Administration: Glass RJ, Glass LM, Beyeler WE, Min HJ. Targeted Social Distancing Designs for Pandemic Influenza. Emerg Infect Dis. 2006;12(11):1671-1681. https://dx.doi.org/10.3201/eid1211.060255
. . . The measures embraced by Drs. Mecher and Hatchett would “result in significant disruption of the social functioning of communities and result in possibly serious economic problems,” Dr. Henderson wrote in his own academic paper responding to their ideas. . . .
. . . Thus did some of the most highly trained and experienced experts on epidemics warn with biting rhetoric against everything that the advocates of lockdown proposed. It was not even a real-world idea in the first place and showed no actual knowledge of viruses and disease mitigation . . .
Despite the refutation of it, and even ridicule, the Bush Administration adopted the made-up totalitarian lockdown rationale.
The 2006 study refuting the lockdown advocacy study is at the bottom of the above article and also this one:
How a Free Society Deals with Pandemics, According to Legendary Epidemiologist and Smallpox Eradicator Donald Henderson by Edward Peter Stringham | May 21, 2020
Disease Mitigation Measures in the Control of Pandemic Influenza
(Biosecurity and Bioterrorism: Biodefense Strategy, Practice, and Science; Volume 4, Number 4, 2006)
By Thomas V. Inglesby, Jennifer B. Nuzzo, Tara O’Toole, and D.A. Henderson
Just to mention one subject:
It has been recommended that individuals maintain a distance of 3 feet or more during a pandemic so as to diminish the number of contacts with people who may be infected. The efficacy of this measure is unknown . . .
This study refers also to specific government documents (one apparently published in 2005) that recommend or relate to the idea of standing a certain distance apart:
 U.S. Department of Health and Human Services. HHS Pandemic Influenza Plan. Washington, DC: U.S. Department of Health and Human Services; November 2005. Available at: http://www.hhs.gov/pandemicflu/plan/pdf/HHSPandemicInfluenzaPlan.pdf. Accessed June 29, 2006.
 U.S. Department of Health and Human Services, Federal Occupational Health. Top 10 Tips for Pandemic Preparedness and Prevention. Available at: http://www.foh.dhhs.gov/public/pandemicinfo/top10tips.pdf#search%22maintain%20distance%203%20feet%20influenza%20social% Accessed September 10, 2006.
Related study which apparently refers to the spread of droplets:
 Toner E. Do public health and infection control measures prevent the spread of flu? Biosecur Bioterror 2006;4(1):84–86.
My comments: I believe these policies–lockdown and social isolation–were deliberately adopted for their socially and economically destructive effects–because they fit with an agenda of introducing a totalitarian society–an agenda that goes back many decades. Now it corresponds to the recent “Great Reset” of the World Economic Forum. It’s clear to me from the writings of H. G. Wells (and others like Bertrand Russell) and from the details of Agenda 21 (and Agenda 2030, etc), that totalitarian control over the population includes vaccines (biological control). Focusing on annual respiratory epidemics becomes a plausible justification for terrifying the public into accepting imposed changes to their society along with transfer of wealth–in the same way that terrorism (9/11) was used to change the laws in order to encroach on civil liberties, and to introduce greater invasions of privacy, for example, with airport security measures and with financial tracking.
Here is a 2007 document from the CDC for pandemic measures:
Social distancing between people is discussed in the document, for example, on page 82:
Determine how the work environment maybe reconfigured to allow for more distance between employees and between employees and customers during a pandemic. If social distancing is not feasible in some work settings, employ other protective measures
This document is extreme–nobody followed it before this year or heard of it–and it’s still not as extreme as what has been done in 2020.