Evaluating the effectiveness of social distancing interventions against COVID-19

Laura Matrajt; Tiffany Leung

relative to the epidemic curve. If the intervention is put in place (and lifted) early on in the epidemic, it results in a delay of the epidemic, but if the intervention occurs later on, then it results in flattening the curve. Indeed, the effectiveness of the intervention will depend on the ratio of the number of susceptible, infected and recovered people in the population at the beginning of the intervention. There is evidence that recovered individuals will have immunity to COVID-19 [31] but it is unclear at this point how long this immunity will last. Recovered individuals would be able to re-enter the work force and help the most vulnerable groups. It is then of paramount importance to have an accurate estimate of the number of current and recovered cases to evaluate possible interventions. As of March 12, 2020, the US had tested fewer than 15,000 CDC samples (in contrast to over 200,000 tests performed in South Korea by mid-March) [32] . It is imperative to expand the testing capabilities in all countries affected.