In December 2021, an outbreak of the SARS-CoV-2 B.1.640.2 variant, potentially originating from Cameroon, was investigated among schoolchildren in Germany. The index case, an adult who had recently returned from a three-week stay in the Republic of Congo, introduced the variant into a school setting via their children, resulting in subsequent transmission within the school and ultimately to a hospital ward. Whole-genome sequencing of viral samples identified both B.1.640.1 and B.1.640.2 lineages. This outbreak highlights the unpredictable nature of emerging SARS-CoV-2 variants and emphasizes the importance of early detection and containment to mitigate transmission to high-risk populations. Notably, wastewater surveillance detected the variant during the study peri-od, reinforcing the utility of wastewater-based epidemiology as a complementary tool for the early warning and containment of novel variants. These findings underline the critical need for timely research and adherence to quarantine measures to enhance outbreak control efforts.