Rapid diagnostic tests for SARS-CoV-2 antigen (RDTs) are an established point-of-care solution for diagnosis, screening and self-testing. On the other hand, the use of the reference standard in SARS-CoV-2 testing—the reverse transcription-quantitative polymerase chain reaction (RT-qPCR)—is limited by diagnostic capacities and infrastructural requirements. However, since the establishment of RDTs, the SARS-CoV-2 wild-type strain has been replaced by SARS-CoV-2 variants of concern (VOC). For this reason, the primary focus of our study is on the impact of the omicron sub-lineage BA.4/5 on RDT performance.