Three-question Summary Box 49 1.) What is the current understanding of this subject? 50 Recent research has been conducted by various countries and regions on the impact of non-51 pharmaceutical interventions (NPIs) on reducing the spread of COVID19. 52 2.) What does this report add to the literature? 53 Our report assessed which intervention strategies provided the best results in terms of both 54 reducing infection outcomes (cases, deaths, etc.) and minimizing their social and economic 55 effects (e.g., number of people homebound, providing childcare, etc.). 3.) What are the implications for public health practice? 57 Voluntary quarantine proved to be the most beneficial in terms of reducing infections and deaths 58 compared to the number of people who were homebound.
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The copyright holder for this preprint this version posted July 24, 2020. . https: //doi.org/10.1101 //doi.org/10. /2020 Some NPIs, such as shelter-in-place, apply to large populations for an extended duration, whereas 76 others, such as voluntary quarantine, impact targeted populations for a limited time. It is important to 77 understand the tradeoffs between the public health benefits and other consequences of NPIs, 78 particularly, as measured by homebound person-days or the size of the homebound population over 79 time. There is sparse research on assessing which interventions have a higher overall impact in reducing 80 societal interactions versus the ability to reduce infection spread and adverse outcomes 8, 9, 24, 25 .
This study evaluates the trade-offs between the public health impact measures (e.g., the number of cases, 
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The copyright holder for this preprint this version posted July 24, 2020 . . https://doi.org/10.1101 Intervention Analysis
The following NPIs, with varying combinations and compliance levels in different scenarios (Figure 1 Table B1 ).
• Homebound: For adults and elderly, this status is defined as staying home due to voluntary 112 quarantine, symptoms, shelter-in-place, or at home childcare, i.e., providing supervision to a 113 child who is home due to their status (e.g., due to symptoms or school closure). For example, if a 114 child is at home in need of supervision, the status of an adult or elderly member in the household 115 is updated to indicate that they provide supervision, labeled as at home childcare. For children 116 and youth, homebound is defined as staying home due to voluntary quarantine, symptoms, or 117 school closure.
• Inactive: For adults and elderly, a status of inactive refers to being inactive from society due to 119 being homebound, hospitalized, or providing hospital care, i.e., caring for a child or youth who 120 became hospitalized. A status of inactive for children and youth is defined as being inactive from 121 society due to being homebound or hospitalized. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 24, 2020. Table B2 . The infection spread measures are contrasted with the following intervention metrics, which are reported 134 for the study period:
• Homebound or inactive subpopulation: Number of people in a subpopulation (adults/elderly or 136 children/youth) with homebound or inactive status, respectively, on a given day.
• Percentage of days adults homebound or inactive: Average percentage of days an adult has 138 homebound or inactive status, respectively.
• Homebound days: Average number of days a (sub)population has homebound status.
• Homebound or inactive peak day: The day when the number of a (sub)population has 141 homebound or inactive status, respectively, is highest.
• Homebound or inactive peak: The highest number (or percentage) of a (sub)population 143 homebound or inactive, respectively, on a given day.
• Adults absent from work: The number of adults who are absent from work due to an inactive 145 status (further details are provided in Supplementary Material Section B).
• Homebound days to prevent an infection: Additional adult homebound days needed to prevent an 147 infection (in Scenario X, relative to Scenario 1), calculated as follows:
• Homebound days to prevent a death: Additional adult homebound days needed to prevent a death 152 (in Scenario X, relative to Scenario 1), calculated as follows:
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The copyright holder for this preprint this version posted July 24, 2020. . https://doi.org/10. 1101 
Supplementary Material Table B2 presents the infection spread outcome measures, including the 159 population infected or dead and the peak infection. Table B2 ). respectively. Compared to Scenario 2 (school closure only), Scenarios 5a, 5b, 5c (shelter-in-place with 184 school closure) reduced the percentage of the total population infected from 51.69% to 48.11-50.55% 185 but more than doubled the percentage of days adults homebound to a range of 18.92-30.66%.
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The copyright holder for this preprint this version posted July 24, 2020. . https://doi.org/10. 1101 Supplementary Material Table B3 provides the percentage of days children, youth, adults, and elderly CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 24, 2020. School closure alone had limited impact on reducing the spread of COVID19. Compared to no 239 intervention, school closure only reduced the percentage of the population infected by less than 10% 240 while more than doubling the peak number of adults homebound and causing nearly 450,000 work 241 absences, the majority of which due to the need to provide at home childcare.
Shelter-in-place combined with school closure (Scenarios 5a-5c) temporarily slowed down the infection 244 spread and delayed the peak, but had little impact on the magnitude of the peak and the cumulative 245 number of infections and deaths, which were similar to that observed in the school closure only scenario.
However, under Scenarios 5a-5c, the peak number of homebound adults was 9-44 times larger than all 247 other intervention scenarios. Hence, the limited positive public health impact of shelter-in-place came at 248 a very high societal cost. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 24, 2020. . https://doi.org/10. 1101 Under voluntary quarantine (Scenarios 3a, 3b, 3c) the percentage of the population infected was CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 24, 2020. If facemask usage was also considered in the NPI scenarios, the relative reduction in the number of 288 cases and deaths could be higher compared to baseline scenarios. The simulation was populated with 289 data from the state of Georgia and the results presented may not apply to other states or regions which 290 have significantly different population characteristics or density. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
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The copyright holder for this preprint this version posted July 24, 2020. . https://doi.org/10. 1101 