Re-estimation of basic reproduction number of COVID-19 based on the epidemic curve by symptom onset date

Hong, K.; Yum, S. J.; Kim, J. H.; Chun, B. C.

Previous studies have reported the basic reproduction number (R(0)) of coronavirus disease from publicly reported data that lack information such as onset of symptoms, presence of importations or known super-spreading events. Using data from the Republic of Korea, we illustrated how estimates of R(0) can be biased and provided improved estimates with more detailed data. We used COVID-19 contact trace system in Korea, which can provide symptom onset date and also serial intervals between contacted people. The total R(0) was estimated as 2.10 (95% confidence interval (CI) 1.84–2.42). Also, early transmission of COVID-19 differed by regional or social behaviours of the population. Regions affected by a specific church cluster, which showed a rapid and silent transmission under non-official religious meetings, had a higher R(0) of 2.40 (95% CI 2.08–2.77).