Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. School closures, physical-distancing, shielding older adults ≥70 years, and quarantining symptomatic COVID-19 patients were all likely to reduce the basic reproduction number (R0).

2. R0 reductions were insufficient across individual intervention methods to avoid overwhelming healthcare systems.

3. Periods of lockdown was the only intervention to reduce R0 to ≤1, and projected to be necessary over the majority of the coming year to prevent exceeding healthcare capacity.

Evidence Rating Level: 2 (Good)

Infectious disease models and projections have been essential in determining public policy to reduce transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19. This age-structured transmission dynamic modelling study conducted in the United Kingdom aimed to determine the potential effects of four control measures for reducing COVID-19 burden through a stochastic, age-structured transmission model: (1) school closures, (2) physical-distancing, (3) shielding of older adults ≥70 years, and (4) quarantining of symptomatic patients. Each of these control measures, as well as in combination, were utilized to project new cases, patients requiring inpatient care, deaths, and the basic reproduction number (R0). In the United Kingdom, by December 2021, this study projected a median unmitigated burden of 23 million cases and 350,000 COVID-19-related deaths. While each of the four interventions were likely to decrease R0, which is a critical value in determining actionable steps during this pandemic, these reductions were insufficient to avoid exceeding health service capacity. School closures alone for example, had little effect on projections, despite them being a core part of many national strategies to reduce spread. A combination of these interventions was most effective in reducing R0 but only periods of lockdown were found to adequately reduce R0 to ≤1. The strictest of these lockdown periods resulted in an estimated 120,000 cases and 50,000 deaths, significantly lower than the unmitigated projections. Overall, this modelling study suggests that lockdown periods, while detrimental to health in many ways (e.g., psychological), may be necessary for the larger part of the coming year to avoid overwhelming healthcare systems and reducing R0 to the degree possible.

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