Serial intervals for SARS-CoV-2 Omicron and Delta variants, Belgium, November 19-December 31, 2021

Abstract: We investigated the serial interval for SARS-CoV-2 Omicron BA.1 and Delta variants and observed a shorter serial interval for Omicron, suggesting faster transmission. Results indicate a relationship between empirical serial interval and vaccination status for both variants. Further assessment of the causes and extent of Omicron dominance over Delta is warranted.