Background: Despite the approval of BNT162b2 mRNA vaccine for children aged 6 months to 4 years by the European Medicines Agency (EMA) and the Federal Drug Administration (FDA) in 2022, no data on vaccine effectiveness (VE) of BNT162b2 are available in this age group. We here report on the VE of BNT162b2 during an Omicron BA.1-2 dominant period.
Methods: An authentication-based retrospective survey was performed between April 14th 2022 and May 9th 2022 in individuals that had registered children for off-label SARS-CoV-2 vaccination in Germany. We used Cox regression to estimate relative VE of two BNT162b2 doses, with the period between first and second vaccine dose as reference period (24.8+-0.6 days) and >=7 days after Dose 2 to before Dose 3 as post-vaccination period (59.5+-23.6 days). Results: The present analysis included 4615 children aged 2.8+-1.2 years (mean+-standard deviation) who had received their first dose of BNT162b2 on January 1st 2022 or thereafter. VE was substantial for protection from any SARS-CoV-2 infection (VE: 53.1% [95% confidence interval (CI): 36.3-69.6%], pppvariants.