Effect of Nonpharmaceutical Interventions on Transmission of Severe Acute Respiratory Syndrome Coronavirus 2, South Korea, 2020

Abstract

We analyzed transmission of coronavirus disease outside of the Daegu-Gyeongsangbuk provincial region in South Korea. We estimated that nonpharmaceutical measures reduced transmissibility by a maximum of 34% without resorting to a strict lockdown strategy. To optimize epidemic control, continuous efforts to monitor the transmissibility are needed.

Keywords: 2019 novel coronavirus disease; COVID-19; SARS-CoV-2; South Korea; coronavirus disease; public health measures; respiratory infections; severe acute respiratory syndrome coronavirus 2; transmissibility; viruses; zoonoses.

Figure 1

Timeline (A) and geographic distribution (B) of laboratory-confirmed cases of coronavirus disease in South Korea as of April 21, 2020. *Daegu-Gyeongsanbuk provincial region.

Figure 2

Incidence and estimated daily effective reproductive number (R_t ) of coronavirus disease in regions outside of Daegu-Gyeongsanbuk provincial region, South Korea, as of April 21, 2020. A) The epidemic curve shows the daily number of patients with confirmed cases and symptom onset. For case-patients who did not report any symptoms on the date of case confirmation (n = 1,205 cases; 60% of total), the date of confirmation was plotted instead. B) Daily estimated R_t and 95% CrI of R_t; shading indicates the area below the epidemic threshold of R_t = 1. The vertical dashed line indicates the start of the highest public alert on February 23, 2020. CrI, credible interval.