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.
Keywords: Belgium; COVID-19; SARS-CoV-2; coronavirus disease; respiratory infections; serial interval; severe acute respiratory syndrome coronavirus 2; vaccine-preventable diseases; variants of concern; viruses; zoonoses.