Scientific American: Omicron’s Surprising Anatomy Explains Why It Is Wildly Contagious

The Omicron variant of the COVID-19 virus is likely the fastest-spreading virus in human history. Omicron is so contagious that one infection can create six new cases after just four days, and more than 200 cases after 12 days. As a comparison, the measles virus might infect only 15 other people in 12 days. Projections estimate that up to 40 percent of the population will be infected by the variant by mid-February. So why is it so contagious even compared to previous strains? Scientists are reaching a consensus that the reason Omicron is so transmissible is that it has an unparalleled ability to hide from the immune system.

The mechanism that allows the COVID-19 virus to grab onto human cells is a fist-shaped clump of amino acids called receptor-binding domains (RBDs). In previous variants, only a handful of amino acids on RBDs were mutated, which prevents some but not all antibodies from recognizing the virus. However, the Omicron variant has 15 RBD mutations, which forms an elaborate disguise and prevents antibodies from recognizing the variant. For more information on why the Omicron variant is so contagious, click here. For more information on vaccines and COVID-19, click here.