Incubation period of wild type of SARS-CoV-2 infections by age, gender, and epidemic periods.

BACKGROUND

The incubation period of the coronavirus disease 2019 (COVID-19) is estimated to vary by demographic factors and the COVID-19 epidemic periods.

OBJECTIVE

This study examined the incubation period of the wild type of SARS-CoV-2 infections by the different age groups, gender, and epidemic periods in South Korea.

METHODS

We collected COVID-19 patient data from the Korean public health authorities and estimated the incubation period by fitting three different distributions, including log-normal, gamma, and Weibull distributions, after stratification by gender and age groups. To identify any temporal impact on the incubation period, we divided the study period into two different epidemic periods (Period-1: 19 January-19 April 2020 and Period-2: 20 April-16 October 2020), and assessed for any differences.

RESULTS

We identified the log-normal as the best-fit model. The estimated median incubation period was 4.6 (95% CI: 3.9-4.9) days, and the 95th percentile was 11.7 (95% CI: 10.2-12.2) days. We found that the incubation period did not differ significantly between males and females ( = 0.42), age groups ( = 0.60), and the two different epidemic periods ( = 0.77).

CONCLUSIONS

The incubation period of wild type of SARS-CoV-2 infection during the COVID-19 pandemic 2020, in South Korea, does not likely differ by age group, gender and epidemic period.