Fig. 3

Serial interval distribution of SARS-CoV-2 in the first and second epidemic waves in South Korea. The estimated serial interval distribution was analysed by using the 698 infector-infectee pairs. The vertical bars indicate the empirical probability density of serial interval calculated by constructing transmission pairs from illness onset of confirmed cases and black lines indicate fitted normal distribution (accounting for the possible negative serial intervals/pre-symptomatic transmissions and symmetric pattern of empirical density). Infector who reported symptoms onset in the first epidemic wave (19 January–19 April 2020; 341 pairs) (A), and second pandemic wave (20 April–11 August 2020; 357 pairs) (B). The left of vertical dashed line in grey indicates definite pre-symptomatic transmission