The spike (S) glycoprotein of coronaviruses is essential for binding of the virus to the host cell at the beginning of the infection process. During the actual COVID-19 pandemic, several variants of the virus evolved and some of them are continuously spreading all over the world. This SARS-CoV-2 variant assigned as "Omicron" by the World Health Organization (WHO) is belonging to Pango lineage B.1.1.529. It is characterised by 30 changes, three small deletions and one small insertion in the spike protein, of these, 15 are in the receptor binding domain. Since the Omicron variant is the most divergent variant that has been detected in significant numbers during the pandemic so far, many concerns raised that it may be associated with increased transmissibility, significant reduction in vaccine effectiveness and increased risk for reinfections. Actually, researchers all over the world are looking with highest priority into any potential impact the Omicron variant has on the effectiveness of COVID-19 vaccines. As of 26 November 2021, ECDC has classified this variant as a variant of concern (VOC).
