Bae: Author Response: Coronavirus Disease 2019 (COVID-19), Infectivity, and the Incubation Period
Dear Editor,
I would like to thank Joob and Wiwanitkit for their perceptive questions.
On February 1, 2020 at the start of the epidemiological survey, the most important issue was to assess the development of coronavirus disease 2019-related symptoms and/or signs in the patient during her stay on Jeju Island. However, the patient had already been admitted to a quarantine hospital in China, so I could not contact her directly. Instead, I contacted her daughter, since they were traveling companions. Using WeChat ( with the assistance of an interpreter, I asked whether the patient’s symptoms appeared during their stay on Jeju Island and inquired about the route of their tour. She stated that her mother’s fever started on January 26, 2020. Therefore, the author interpreted that the patient’s stay on Jeju Island—between January 21, 2020 (-5 days) and January 25, 2020 (-1 day)—was during the incubation period. This estimate was based on a previous report, published on January 29, 2020, stating that the mean incubation period was 5.2 days (95% confidence interval, 4.1 to 7.0) [1].


The authors have no conflicts of interest associated with the material presented in this paper.


1. Li Q, Guan X, Wu P, Wang X, Zhou L, Tong Y, et al. Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. N Engl J Med 2020;382(13):1199-1207.
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